How to implement js to remove spaces before and after a string_javascript skills

When we do some page editing, the spaces before and after the string are usually invalid. Therefore, filtering is required when obtaining information.

For example:

　Enter : [space][space]a[space]b[space][space][space]

　gets: a[space]b

The code is as follows:
Remove leading spaces

function LTrim(str){ 
  var i; 
  for(i=0;i<str.length;i++){
    if(str.charAt(i)!=" ") 
      break; 
  } 
  str = str.substring(i,str.length); 
  return str; 
}

Remove the following spaces

function RTrim(str){ 
  var i; 
  for(i=str.length-1;i>=0;i--){ 
    if(str.charAt(i)!=" ") 
      break; 
  } 
  str = str.substring(0,i+1); 
  return str; 
}

How to use

function Trim(str){ 
   return LTrim(RTrim(str)); 
 }

【Recommended】Use the regular method

String.prototype.Trim = function(){ 
  return this.replace(/(^\s*)|(\s*$)/g, ""); 
} 

String.prototype.LTrim = function(){ 
  return this.replace(/(^\s*)/g, ""); 
} 

String.prototype.RTrim = function(){ 
  return this.replace(/(\s*$)/g, ""); 
} 

Added some other methods:

The first type: loop check and replace

//供使用者调用 
function trim(s){ 
return trimRight(trimLeft(s)); 
} 
//去掉左边的空白 
function trimLeft(s){ 
if(s == null) { 
return ""; 
} 
var whitespace = new String(" \t\n\r"); 
var str = new String(s); 
if (whitespace.indexOf(str.charAt(0)) != -1) { 
var j=0, i = str.length; 
while (j < i && whitespace.indexOf(str.charAt(j)) != -1){ 
j++; 
} 
str = str.substring(j, i); 
} 
return str; 
} 
//去掉右边的空白 www.jb51.net 
function trimRight(s){ 
if(s == null) return ""; 
var whitespace = new String(" \t\n\r"); 
var str = new String(s); 
if (whitespace.indexOf(str.charAt(str.length-1)) != -1){ 
var i = str.length - 1; 
while (i >= 0 && whitespace.indexOf(str.charAt(i)) != -1){ 
i--; 
} 
str = str.substring(0, i+1); 
} 
return str; 
} 

The second method: cutting strings

function trim(str){ 
str = str.replace(/^(\s|\u00A0)+/,''); 
for(var i=str.length-1; i>=0; i--){ 
if(/\S/.test(str.charAt(i))){ 
str = str.substring(0, i+1); 
break; 
} 
} 
return str; 
} 

The above are various ways to remove spaces before and after strings in js. I hope it will be helpful to everyone's learning.