Selectors API_html/css_WEB-ITnose
HTML5向Web API新引入了
document.querySelectordocument.querySelectorAll
两个方法用来更方便地从DOM选取元素，功能类似于jQuery的选择器。这使得在编写原生JavaScript代码时方便了许多。
querySelector
该方法返回满足条件的单个元素。按照深度优先和先序遍历的原则使用参数提供的CSS选择器在DOM进行查找，返回第一个满足条件的元素。
querySelectorAll
该方法返回所有满足条件的元素，结果是个nodeList集合。查找规则与前面所述一样。
<!DOCTYPE html><html> <body> <h3 id="h-元素"> h3 元素</h3> <h2 id="h-元素"> h2 元素</h2> <script> //querySelector会给所有元素的第一个元素加上样式 document.querySelector("h2, h3").style.backgroundColor = "red"; </script> </body></html><!DOCTYPE html><html> <body> <h2 id="h-元素"> h2 元素</h2> <h3 id="h-元素"> h3 元素</h3> <script> //querySelectorAll获取所有元素，返回一个list集合 var o2 = document.querySelectorAll("h2, h3"); for(var i in o2){ o2[i].style.backgroundColor = "red"; } </script> </body></html>
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