dhDataGrid Ver2.0.0 code of javascript_form effects
Updated for the previous version of dhDataGrid Ver1.0.0!
1. The fixed mode of the title bar and left sidebar is updated, and the expression mode is cancelled;
2. The sorting mode is updated, and it also supports the sorting of numbers, characters, dates, mixed numbers and characters, and Chinese characters;
3. Support skin change, you can customize the control style yourself;
4. Reserve [double-click], [right-click] functions;
5. Support IE, FF;
CSS:
/*dhdatagrid block style*/
#dhdatagrid {position:relative;width:500px;height:200px;background:white;margin :0px;padding:0px;overflow:hidden;border:1px inset;-moz-user-select:none;}
/*dhdatagrid table global style*/
#dhdatagrid table {table-layout:fixed; margin:0px;}
#dhdatagrid table td {height:18px;cursor:default;font-size:12px;font-family:verdana;overflow:hidden;white-space:nowrap;text-indent:2px;border -right:1px solid buttonface;border-bottom:1px solid buttonface;}
#dhdatagrid table td .arrow {font-size:8px;color:#808080;}
#dhdatagrid table .lastdata {border-right :none;}
#dhdatagrid table .column {width:120px;cursor:default;background:buttonface;border-top:1px solid #fff;border-right:1px solid #404040;border-bottom:1px solid # 404040;border-left:1px solid #fff;}
#dhdatagrid table .over {width:120px;cursor:default;background:buttonface;border-top:1px solid #fff;border-right:1px solid #404040 ;border-bottom:1px solid #404040;border-left:1px solid #fff;}
#dhdatagrid table .sortdown {width:120px;cursor:default;background:buttonface;border-right:1px solid #ffffff; border-bottom:1px solid #ffffff;border-left:1px solid #404040;border-top:1px solid #404040;position:relative;left:1px;}
#dhdatagrid table .dataover {background:#FAFAFA; }
#dhdatagrid table .firstcolumn {width:30px;text-indent:0px;text-align:center;background:buttonface;border-top:1px solid #fff;border-right:1px solid #404040;border- bottom:1px solid #404040;border-left:1px solid #fff;}
#dhdatagrid table .lastcolumn {background:buttonface;border-top:1px solid #fff;border-right:1px solid #404040;border- bottom:1px solid #404040;border-left:1px solid #fff;}
/*dhdatagrid selected row style*/
#dhdatagrid table .selectedrow {background:highlight;color:white;}
/*dhdatagrid header style*/
#dhdatagrid #titlecolumn {width:100%;position:absolute;top:0px;left:0px;z-index:3;}
/*dhdatagrid left column style* /
#dhdatagrid #slidecolumn {width:30px;position:absolute;top:0px;left:0px;z-index:2;}
#dhdatagrid #slidecolumn td {width:30px;text-indent:0px ;text-align:center;background:buttonface;border-top:1px solid #fff;border-right:1px solid #404040;border-bottom:1px solid #404040;border-left:1px solid #fff;}
/*dhdatagrid content table body style*/
#dhdatagrid #datacolumn {width:100%;position:absolute;top:0px;left:0px;}
/*dhdatagrid origin style*/
# dhdatagrid #zero {width:30px;height:18px;margin:0px;padding:0px;position:absolute;top:0px;left:0px;z-index:10;background:buttonface;border-top:1px solid #fff ;border-right:1px solid #404040;border-bottom:1px solid #404040;border-left:1px solid #fff;text-align:center;font-size:10px;color:#A19F92;}
JS:
function dhdatagrid(){
//author:dh20156;
this.callname = "dhdg";
this.width = 500;
this.height = 200;
this.rid = "dhdatagrid";
this.columns = [];
this.data = [];
this.dblclick_fun = function(){}
this.contextmenu_fun = function(){}
this.parentNode = document.body;
var dh = this;
var framediv = null;
var zerobj = null;
var leftobj = null;
var titleobj = null;
var dataobj = null;
var hbar = null;
var vbar = null;
var bgbar = null;
//Change the initial position of the column width
var ml = 0;
//Change the initial width of the column width object
var ow = 0;
//Change the column width object
var tdobj = null;
//Current selection Fixed row index
var nowrow = null;
//Whether to change the vertical scroll bar position
var changeposv = true;
this.init = function(){
//init the data initial data
var dgc = "";
if(this.columns.length>0){
dgc = "
for(var cc=0;cc
}
dgc = "
}
var dgs = "";
var dgd = "";
if(this.data.length> 0){
//First column
dgs = " ";
for(var r=0;r
dgd = " ";
for( var c=0;c
}
dgd = "
}
if(dgc==""){
dgc = " ";
for(var dc=0;dc
}
dgc = "
}
}
//dhdatagrid frame frame
var dgframe = document.createElement(" DIV");
dgframe.id = this.rid;
dgframe.onmousedown = function(e){e=e||window.event;getrow(e);}
dgframe.onmousemove = function (e){e=e||window.event;rsc_m(e);}
if(document.attachEvent){
document.attachEvent("onmouseup",rsc_u);
}else{
document.addEventListener("mouseup",rsc_u,false);
}
dgframe.oncontextmenu = function(){return false}
dgframe.onselectstart = function(){return false}
ae(dgframe);
//dhdatagrid zero point zero point
var dgzero = ""
//dhdatagrid slidecolumn first column
var dgslide = "" dgs "
//dhdatagrid column title bar
var dgcolumn = "" dgc "
//dhdatagrid data data
var dgdata = "" dgc dgd "
//dhdatagrid hbar 水平滚动条
var dghbar = document.createElement("DIV");
dghbar.id = "hbar";
dghbar.style.position = "absolute";
dghbar.style.width = "100%";
dghbar.style.height = "17px";
dghbar.style.top = this.height-17;
dghbar.style.overflowX = "auto";
dghbar.style.zIndex = "10";
dghbar.onscroll = function(){scrh();}
dghbar.innerHTML = "
//dhdatagrid vbar 垂直滚动条
var dgvbar = document.createElement("DIV");
dgvbar.id = "vbar";
dgvbar.style.position = "absolute";
dgvbar.style.width = "17px";
dgvbar.style.height = "100%";
dgvbar.style.left = this.width-17;
dgvbar.style.overflowY = "auto";
dgvbar.style.zIndex = "10";
dgvbar.onscroll = function(){scrv();}
dgvbar.innerHTML = "
//dhdatagrid bgbar 滚动条背景
var dgbgbar = document.createElement("DIV");
dgbgbar.id = "bgbar";
dgbgbar.style.background = "buttonface";
dgbgbar.style.position = "absolute";
dgbgbar.style.width = "100%";
dgbgbar.style.height = "17px";
dgbgbar.style.top = this.height-17;
dgbgbar.style.overflowX = "auto";
dgbgbar.style.zIndex = "9";
dgbgbar.style.display = "none";
dgbgbar.innerHTML = " ";
//appendChild
dgframe.innerHTML = dgzero dgslide dgcolumn dgdata;
dgframe.appendChild(dghbar);
dgframe.appendChild(dgvbar);
dgframe.appendChild(dgbgbar);
this.parentNode.appendChild(dgframe);
if(document.attachEvent){
document.attachEvent("onkeydown",updown);
}else{
document.addEventListener("keydown",updown,false);
}
framediv = dgframe;
zerobj = document.getElementById("zero");
leftobj = document.getElementById("slidecolumn");
titleobj = document.getElementById("titlecolumn");
dataobj = document.getElementById("datacolumn");
hbar = dghbar;
vbar = dgvbar;
bgbar = dgbgbar;
var btt = getCurrentStyle(framediv,"borderTopWidth");
var btr = getCurrentStyle(framediv,"borderRightWidth");
var btb = getCurrentStyle(framediv,"borderBottomWidth");
var btl = getCurrentStyle(framediv,"borderLeftWidth");
var fh = getCurrentStyle(framediv,"height");
var zh = getCurrentStyle(zerobj,"height");
var zbt = getCurrentStyle(zerobj,"borderTopWidth");
var zbb = getCurrentStyle(zerobj,"borderBottomWidth");
if(document.all){
vbar.style.left = parseInt(vbar.style.left)-parseInt(btr)-parseInt(btl);
}else{
framediv.style.height = parseInt(fh)-parseInt(btb)-parseInt(btt);
zerobj.style.height = parseInt(zh)-parseInt(zbb)-parseInt(zbt);
}
hbar.style.top = parseInt(hbar.style.top)-parseInt(btb)-parseInt(btt);
bgbar.style.top = parseInt(bgbar.style.top)-parseInt(btb)-parseInt(btt);
}
function getCurrentStyle(oElement, sProperty) {
if(oElement.currentStyle){
return oElement.currentStyle[sProperty];
}else if(window.getComputedStyle){
sProperty = sProperty.replace(/([A-Z])/g, "-$1").toLowerCase();
return window.getComputedStyle(oElement, null).getPropertyValue(sProperty);
}else{
return null;
}
}
//设置块滚动条
this.setwh = function(){
hbar.style.display = "block";
vbar.style.display = "block";
hbar.childNodes[0].style.width = dataobj.offsetWidth;
vbar.childNodes[0].style.height = dataobj.offsetHeight;
if(hbar.childNodes[0].offsetWidth hbar.style.display = "none";
}else{
hbar.style.display = "block";
}
if(vbar.childNodes[0].offsetHeight vbar.style.display = "none";
}else{
vbar.style.display = "block";
}
if(hbar.childNodes[0].offsetWidth>hbar.offsetWidth && vbar.childNodes[0].offsetHeight>vbar.offsetHeight && changeposv){
bgbar.style.display = "block";
hbar.style.width = hbar.offsetWidth-17;
vbar.style.height = vbar.offsetHeight-17;
vbar.childNodes[0].style.height = vbar.childNodes[0].offsetHeight 17;
changeposv = false;
}
if(hbar.childNodes[0].offsetWidth bgbar.style.display = "none";
hbar.childNodes[0].style.width = 0;
hbar.style.width = hbar.offsetWidth 17;
vbar.style.height = vbar.offsetHeight 17;
changeposv = true;
if(vbar.offsetHeight-dataobj.offsetHeight>dataobj.offsetTop && document.all){
leftobj.style.top = leftobj.offsetTop 17;
dataobj.style.top = dataobj.offsetTop 17;
}
}
}
//鼠标滚轮,列表滚动事件
function mwEvent(e){
e=e||window.event;
if(e.wheelDelta0){
vbar.scrollTop = 18;
}else {
vbar.scrollTop -= 18;
}
}
function ae(obj){
if(document.attachEvent){
obj.attachEvent("onmousewheel",mwEvent);
}else{
obj.addEventListener("DOMMouseScroll",mwEvent,false);
}
}
//滚动条事件
function scrv(){
leftobj.style.top = -(vbar.scrollTop);
dataobj.style.top = -(vbar.scrollTop);
}
function scrh(){
titleobj.style.left = -(hbar.scrollLeft);
dataobj.style.left = -(hbar.scrollLeft);
}
//选择行
function getrow(e){
e=e||window.event;
var esrcobj = e.srcElement?e.srcElement:e.target;
if(esrcobj.parentNode.tagName=="TR"){
var epobj = esrcobj.parentNode;
var eprowindex = epobj.rowIndex;
if(eprowindex!=0){
if(nowrow!=null){
dataobj.rows[nowrow].className = "";
}
dataobj.rows[eprowindex].className = "selectedrow";
nowrow = eprowindex;
}
}
}
//更改列宽
this.rsc_d = function(e,obj){
var px = document.all?e.offsetX:e.layerX-obj.offsetLeft;
if(px>obj.offsetWidth-6 && px
obj=obj||this;
ml = e.clientX;
ow = obj.offsetWidth;
tdobj = obj;
if(obj.setCapture){
obj.setCapture();
}else{
e.preventDefault();
}
}else{
if(nowrow!=null){
dataobj.rows[nowrow].className = "";
}
if(obj.getAttribute("sort")==null){
obj.setAttribute("sort",0);
}
var sort = obj.getAttribute("sort");
if(sort==1){
dgsort(obj,true);
obj.setAttribute("sort",0);
}else{
dgsort(obj,false);
obj.setAttribute("sort",1);
}
obj.className = "sortdown";
}
}
this.mouseup = function(obj){
obj.className = "over";
}
function rsc_m(e){
if(tdobj!=null){
e=e||window.event;
var newwidth = ow-(ml-e.clientX);
if(newwidth>5){
tdobj.style.width = newwidth;
dataobj.rows[0].cells[tdobj.cellIndex].style.width = newwidth;
}else{
tdobj.style.width = 5;
dataobj.rows[0].cells[tdobj.cellIndex].style.width = 5;
}
dh.setwh();
scrh();
}
}
function rsc_u(e){
if(tdobj!=null){
e=e||window.event;
var newwidth = ow-(ml-e.clientX);
if(newwidth>5){
tdobj.style.width = newwidth;
dataobj.rows[0].cells[tdobj.cellIndex].style.width = newwidth;
}else{
tdobj.style.width = 5;
dataobj.rows[0].cells[tdobj.cellIndex].style.width = 5;
}
if(tdobj.releaseCapture){
tdobj.releaseCapture();
}
ml = 0;
ow = 0;
tdobj = null;
}
dh.setwh();
scrh();
}
this.cc = function(e,obj){
var px = document.all?e.offsetX:e.layerX-obj.offsetLeft;
if(px>obj.offsetWidth-6 && px
}else{
obj.style.cursor = "default";
}
}
this.over = function(obj){
obj.className = "over";
}
this.out = function(obj){
obj.className = "column";
}
this.dataover = function(obj){
if(obj.rowIndex!=nowrow){
obj.className = "dataover";
}
}
this.dataout = function(obj){
if(obj.rowIndex!=nowrow){
obj.className = "";
}
}
//键盘Up & Down事件
function updown(e){
e=e || window.event; e=e.which || e.keyCode;
var rl = dh.data.length;
switch(e){
case 38://Up;
if(nowrow!=null && nowrow>1){
vbar.scrollTop -= 18;
dataobj.rows[nowrow].className = "";
nowrow -= 1;
dataobj.rows[nowrow].className = "selectedrow";
};
break;
case 40://Down;
if(nowrow!=null && nowrow
dataobj.rows[nowrow].className = "";
nowrow = 1;
dataobj.rows[nowrow].className = "selectedrow";
};
break;
default:break;
}
}
function dti(s){
var n = 0;
var a = s.match(/d /g);
for(var i=0;i
}
}
n = a.join("");
return n;
}
//排序
function dgsort(obj,asc){
var rl = dh.data.length;
var ci = obj.cellIndex;
var rowsobj = [];
for(var i=1;i
}
rowsobj.sort(function(trObj1,trObj2){
if(!isNaN(trObj1.cells[ci].innerHTML.charAt(0)) && !isNaN(trObj2.cells[ci].innerHTML.charAt(0))){
if(asc){
return dti(trObj1.cells[ci].innerHTML)-dti(trObj2.cells[ci].innerHTML);
}else{
return dti(trObj2.cells[ci].innerHTML)-dti(trObj1.cells[ci].innerHTML);
}
}else{
if(asc){
return trObj1.cells[ci].innerHTML.localeCompare(trObj2.cells[ci].innerHTML);
}else{
return trObj2.cells[ci].innerHTML.localeCompare(trObj1.cells[ci].innerHTML);
}
}
});
for(var i=0;i
}
for(var c=1;c
}
if(asc){
obj.childNodes[1].innerHTML = "▲";
}else{
obj.childNodes[1].innerHTML = "▼";
}
}
}
注: DEMO(演示):http://www.jxxg.com/dh20156/dhdatagrid/
原文:http://blog.csdn.net/dh20156/archive/2007/02/08/1505050.aspx
另外一个封装的很简单的grid by 秦皇也爱JS
<script> <BR>var GridData = { <BR> title: ["姓名","性别","年龄","学历","特长"], <BR> type: [0,1,0,1,0], //编辑框类型 ŀ--textbox Ł---select <BR> order: [-1,-1,-1,-1,-1], //排序类型 Ł----升序 -1---降序 <BR> data: [["张三","男",27,"本科","足球"], <BR> ["YM","男",26,"本科","中锋"], <BR> ["McGrady","男",28,"博士","前锋"], <BR> ["James","男",25,"本科","小前锋"], <BR> ["Good","女",21,"高中","商品"], <BR> ["Fut","男",22,"本科","WAR3"], <BR> ["Keens","男",37,"高中","SC"], <BR> ["Gruby","女",32,"本科","SC"], <BR> ["Grrr","男",19,"硕士","SC"], <BR> ["Sky","男",22,"本科","WAR3"], <BR> ["Moon","男",25,"本科","WAR3"]] <BR>}; <br><br>var 性别 = ["男", "女"]; <BR>var 学历 = ["高中", "本科", "硕士", "博士"]; <br><br>function MyGrid(data, cnt){ <BR> MyGrid.backColor = "#fdfdfd"; <BR> MyGrid.hoverColor = "#edfae9"; <BR> MyGrid.clickColor = "#e1e6f1"; <br><br> this.datas = data; <BR> this.container = cnt; <BR> this.table; <BR> this.curRow; <BR> this.curCell; <BR> this.editTools = [document.body.appendChild(document.createElement("input")),document.body.appendChild(document.createElement("select"))]; <BR> var CurGrid = this; <BR> this.load = function(){ //grid重画模块 <BR> /** 加载table **/ <BR> var tbStr = []; <BR> tbStr.push("<table cellspacing='1'><tr height='25'>"); <BR> for(var o in this.datas.title){ <BR> tbStr.push("<th>" + this.datas.title[o] + (this.datas.order[o]==1?"↑":"↓") + ""); <BR> } <BR> tbStr.push(""); <br><br> for(var i in this.datas.data){ <BR> tbStr.push("<tr bgcolor=" + MyGrid.backColor + " height='25'>"); <BR> for(var j in this.datas.data[i]){ <BR> tbStr.push("<td>" + this.datas.data[i][j] + ""); <BR> } <BR> tbStr.push(""); <BR> } <br><br> tbStr.push(""); <BR> this.container.innerHTML = tbStr.join(""); <BR> this.table = this.container.firstChild; <br><br> /** 设置编辑工具 **/ <BR> this.editTools[0].onblur = function(){ <BR> CurGrid.curCell.removeChild(CurGrid.curCell.firstChild) <BR> CurGrid.curCell.appendChild(document.createTextNode(this.value)); <BR> if(isNaN(CurGrid.datas.data[CurGrid.curCell.parentNode.rowIndex-1][CurGrid.curCell.cellIndex])){ <BR> CurGrid.datas.data[CurGrid.curCell.parentNode.rowIndex-1][CurGrid.curCell.cellIndex] = this.value; <BR> }else{ <BR> CurGrid.datas.data[CurGrid.curCell.parentNode.rowIndex-1][CurGrid.curCell.cellIndex] = Number(this.value) <BR> } <br><br> this.value = ""; <BR> this.style.display = "none"; <BR> } <br><br> this.editTools[1].onblur = function(){ <BR> this.options.length = 0; <BR> this.style.display = "none"; <BR> } <br><br> this.editTools[1].onchange = function(){ <BR> CurGrid.curCell.removeChild(CurGrid.curCell.firstChild) <BR> CurGrid.curCell.appendChild(document.createTextNode(this.value)); <BR> CurGrid.datas.data[CurGrid.curCell.parentNode.rowIndex-1][CurGrid.curCell.cellIndex] = this.value; <br><br> this.options.length = 0; <BR> this.style.display = "none"; <BR> } <br><br> /** 设置单元格 **/ <BR> for(var r=1; r<this.table.rows.length;r++){ <BR> this.table.rows[r].onmouseover = function(){ this.style.backgroundColor = MyGrid.hoverColor; } <BR> this.table.rows[r].onmouseout = function(){ <BR> if(CurGrid.curRow!=this) this.style.backgroundColor = MyGrid.backColor; <BR> else this.style.backgroundColor = MyGrid.clickColor; <BR> } <br><br> for(var c=0;c<this.table.rows[r].cells.length;c++){ <BR> this.table.rows[r].cells[c].onclick = function(){ <BR> if(CurGrid.curRow) CurGrid.curRow.style.backgroundColor = MyGrid.backColor; <BR> CurGrid.curRow = this.parentNode; <BR> this.parentNode.style.backgroundColor = MyGrid.clickColor; <BR> } <br><br> this.table.rows[r].cells[c].ondblclick = function(){ <BR> //alert("( " + this.cellIndex + "," + this.parentNode.rowIndex + " ) " + this.firstChild.data); <BR> CurGrid.curCell = this; <br><br> CurGrid.editTools[CurGrid.datas.type[this.cellIndex]].style.display = "block"; <BR> CurGrid.editTools[CurGrid.datas.type[this.cellIndex]].style.width = this.offsetWidth; <BR> CurGrid.editTools[CurGrid.datas.type[this.cellIndex]].style.height = this.offsetHeight; <BR> CurGrid.editTools[CurGrid.datas.type[this.cellIndex]].style.left = getAbsPos(this).leftx - CurGrid.container.scrollLeft; <BR> CurGrid.editTools[CurGrid.datas.type[this.cellIndex]].style.top = getAbsPos(this).topy - CurGrid.container.scrollTop; <BR> CurGrid.editTools[CurGrid.datas.type[this.cellIndex]].focus(); <br><br> if(CurGrid.datas.type[this.cellIndex] == 0){ <BR> CurGrid.editTools[CurGrid.datas.type[this.cellIndex]].select(); <BR> }else if(CurGrid.datas.type[this.cellIndex] == 1){ <BR> CurGrid.loadSelect(CurGrid.datas.title[this.cellIndex]); <BR> } <br><br> CurGrid.editTools[CurGrid.datas.type[this.cellIndex]].value = this.firstChild.data; <BR> } <BR> } <BR> } <br><br> for(var g=0; g<this.table.rows[0].cells.length;g++){ <BR> this.table.rows[0].cells[g].onclick = function(){ <BR> CurGrid.datas.order[this.cellIndex] = -CurGrid.datas.order[this.cellIndex]; <BR> CurGrid.sort(this.cellIndex, CurGrid.datas.order[this.cellIndex]); <BR> } <BR> } <BR> } <br><br> this.sort = function(n, type){ //排序 <BR> this.datas.data = this.datas.data.sort(function(x,y){if (x[n]>y[n]){return type;}else if(x[n]<y[n]){return -type;}else{return 0;}}); <BR> this.load(); <BR> } <br><br> this.delRow = function(){ //删除行 <BR> this.datas.data.splice(this.curRow.rowIndex-1, 1); <BR> this.table.deleteRow(this.curRow.rowIndex); <BR> } <br><br> this.loadSelect = function(type){ //读取下拉框内容 <BR> var opts = this.editTools[1].options; <BR> for(var o in eval(type)){ <BR> var opt = document.createElement("option"); <BR> opt.value = opt.text = eval(type)[o]; <BR> opts.add(opt); <BR> } <BR> } <BR>} <br><br>var grid; <BR>window.onload = loadGrid; <br><br>function loadGrid(){ <BR> grid = new MyGrid(GridData, $("panel")); <BR> grid.load(); <BR>} <br><br>function $(id){ <BR> return document.getElementById?document.getElementById(id):eval(id); <BR>} <br><br>function getAbsPos(obj){ <BR> var objResult = new Object(); <BR> objResult.topy = obj.offsetTop; <BR> objResult.leftx = obj.offsetLeft; <BR> while( obj = obj.offsetParent){ <BR> objResult.topy += obj.offsetTop; <BR> objResult.leftx += obj.offsetLeft; <BR> } <BR> return objResult; <BR>} <br><br></script>

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Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

The shift from C/C to JavaScript requires adapting to dynamic typing, garbage collection and asynchronous programming. 1) C/C is a statically typed language that requires manual memory management, while JavaScript is dynamically typed and garbage collection is automatically processed. 2) C/C needs to be compiled into machine code, while JavaScript is an interpreted language. 3) JavaScript introduces concepts such as closures, prototype chains and Promise, which enhances flexibility and asynchronous programming capabilities.

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python and JavaScript have their own advantages and disadvantages in terms of community, libraries and resources. 1) The Python community is friendly and suitable for beginners, but the front-end development resources are not as rich as JavaScript. 2) Python is powerful in data science and machine learning libraries, while JavaScript is better in front-end development libraries and frameworks. 3) Both have rich learning resources, but Python is suitable for starting with official documents, while JavaScript is better with MDNWebDocs. The choice should be based on project needs and personal interests.

Both Python and JavaScript's choices in development environments are important. 1) Python's development environment includes PyCharm, JupyterNotebook and Anaconda, which are suitable for data science and rapid prototyping. 2) The development environment of JavaScript includes Node.js, VSCode and Webpack, which are suitable for front-end and back-end development. Choosing the right tools according to project needs can improve development efficiency and project success rate.
