JavaScript 查找元素
查询单个元素document.getElementById
示例
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<!DOCTYPE html><html> <head> <title>访问元素</title> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <style> .mycolor{ color:#fff; } </style> </head> <body> <ul id="ul"> <li id="a">油条</li> <li id="b">包子</li> <li id="c">米饺</li> <li id="d"><a>鱼粉</a></li> </ul> <script> // 返回单一元素节点 var el = document.getElementById('a'); el.className='mycolor'; </script> </body></html> |
按CSS查询一个 document.querySelector
按CSS查询
示例1 查询一个
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<!DOCTYPE html><html> <head> <title>访问元素</title> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <style> .mycolor{ color:#fff; } .steam{ text-decoration: initial; } </style> </head> <body> <ul id="ul"> <li id="a">油条</li> <li id="b" class="steam">包子</li> <li id="c" class="steam">米饺</li> <li id="d"><a>鱼粉</a></li> </ul> <script> // 返回一个元素节点 var el = document.querySelector('li.steam'); el.className='mycolor'; </script> </body></html> |
示例2 查询多个
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<!DOCTYPE html><html> <head> <title>访问元素</title> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <style> .mycolor{ color:#fff; } .steam{ text-decoration: initial; } </style> </head> <body> <ul id="ul"> <li id="a">油条</li> <li id="b" class="steam">包子</li> <li id="c" class="steam">米饺</li> <li id="d"><a>鱼粉</a></li> </ul> <script> // 返回多个元素节点 var els = document.querySelectorAll('li.steam'); els[0].className='mycolor'; </script> </body></html> |
按元素标签查询多个 getElementsByTagName
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<!DOCTYPE html><html> <head> <title>访问元素</title> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <style> .mycolor{ color:#fff; } .steam{ text-decoration: initial; } </style> </head> <body> <ul id="ul"> <li id="a">油条</li> <li id="b" class="steam">包子</li> <li id="c" class="steam">米饺</li> <li id="d"><a>鱼粉</a></li> </ul> <script> // 按元素标签查询 var els = document.getElementsByTagName('li'); els[2].className='mycolor'; </script> </body></html> |
查询父节点parentNode
示例
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<!DOCTYPE html><html> <head> <title>访问元素</title> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <style> .mycolor{ color:#fff; } .steam{ text-decoration: initial; } </style> </head> <body> <ul id="ul"> <li id="a">油条</li> <li id="b" class="steam">包子</li> <li id="c" class="steam">米饺</li> <li id="d" ><a id="yufen">鱼粉</a></li> </ul> <script> // 查找父节点 var el = document.getElementById('yufen'); el.parentNode.className="mycolor"; </script> </body></html> |
查找兄弟元素 previousSibling nextSibling
示例
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<!DOCTYPE html><html> <head> <title>访问元素</title> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <style> .mycolor{ color:#fff; } .steam{ color: red; } </style> </head> <body> <ul id="ul"> <li id="ali">油条</li><li id="bli">包子</li><li id="cli">米饺</li><li id="dli"><a id="yufen">鱼粉</a></li> </ul> <script> // 查找父节点 var tempel = document.getElementById("bli"); tempel.className="steam"; var previousNode = tempel.previousSibling; previousNode.className="mycolor"; var nextNode = tempel.nextSibling; nextNode.className="mycolor"; </script> </body></html> |
兄弟元素查找比较坑，只是能元素在同一行时才能查询。
查询子节点 firstChild lastChild
示例
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<!DOCTYPE html><html> <head> <title>访问元素</title> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <style> .mycolor{ color:#fff; } .steam{ color: red; } </style> </head> <body> <ul id="ul" ><li id="ali">油条</li ><li id="bli">包子</li ><li id="cli"><a id="yufen">米饺</a></li ><li id="dli">鱼粉</li ></ul> <script> // 查找子节点 var tempel = document.getElementById("ul"); var firstNode = tempel.firstChild; firstNode.className = "mycolor"; var lastNode = tempel.lastChild; lastNode.className = "mycolor"; </script> </body></html> |