{"id":312749,"date":"2024-05-20T22:46:59","date_gmt":"2024-05-20T14:46:59","guid":{"rendered":"https:\/\/docs.pingcode.com\/ask\/ask-ask\/312749.html"},"modified":"2024-05-20T22:47:30","modified_gmt":"2024-05-20T14:47:30","slug":"javascript-%e7%a8%8b%e5%ba%8f%e4%b8%ad%e6%80%8e%e4%b9%88%e8%8e%b7%e5%8f%96-html-%e7%9a%84-dom-%e8%8a%82%e7%82%b9-2","status":"publish","type":"post","link":"https:\/\/docs.pingcode.com\/ask\/312749.html","title":{"rendered":"JavaScript \u7a0b\u5e8f\u4e2d\u600e\u4e48\u83b7\u53d6 HTML \u7684 DOM \u8282\u70b9"},"content":{"rendered":"

\"JavaScript<\/p>\n

\u5728JavaScript\u7a0b\u5e8f\u4e2d\u83b7\u53d6HTML\u7684DOM\u8282\u70b9\u901a\u5e38\u53ef\u901a\u8fc7\u591a\u79cd\u65b9\u6cd5\u5b9e\u73b0\uff0c\u5305\u62ec\u4f46\u4e0d\u9650\u4e8e document.getElementById()<\/code>\u3001document.getElementsByTagName()<\/code>\u3001document.getElementsByClassName()<\/code>\u3001\u4ee5\u53ca\u66f4\u73b0\u4ee3\u7684\u67e5\u8be2\u65b9\u5f0f document.querySelector()<\/code> \u548c document.querySelectorAll()<\/code><\/strong>\u3002\u5728\u8fd9\u4e9b\u65b9\u6cd5\u4e2d\uff0cdocument.querySelector()<\/code><\/strong> \u7684\u7075\u6d3b\u6027\u548c\u5f3a\u5927\u529f\u80fd\u4f7f\u5176\u6210\u4e3a\u83b7\u53d6DOM\u8282\u70b9\u65f6\u5e38\u7528\u4e14\u63a8\u8350\u7684\u65b9\u6cd5\u3002document.querySelector()<\/code> \u65b9\u6cd5\u63a5\u6536\u4e00\u4e2aCSS\u9009\u62e9\u5668\u5b57\u7b26\u4e32\u4f5c\u4e3a\u53c2\u6570\uff0c\u8fd4\u56de\u6587\u6863\u4e2d\u5339\u914d\u8be5\u9009\u62e9\u5668\u7684\u7b2c\u4e00\u4e2a\u5143\u7d20\u3002\u5982\u679c\u6ca1\u6709\u627e\u5230\u5339\u914d\u9879\uff0c\u8fd4\u56denull<\/code>\u3002\u8fd9\u79cd\u65b9\u5f0f\u5141\u8bb8\u5f00\u53d1\u8005\u4ee5CSS\u9009\u62e9\u5668\u7684\u5f62\u5f0f\uff0c\u975e\u5e38\u7cbe\u786e\u5730\u5b9a\u4f4d\u5230\u6240\u9700\u7684DOM\u5143\u7d20\uff0c\u4ece\u800c\u5927\u5927\u63d0\u9ad8\u4e86\u64cd\u4f5c\u7684\u4fbf\u6377\u6027\u548c\u4ee3\u7801\u7684\u53ef\u8bfb\u6027\u3002<\/p>\n<\/p>\n

\u4e00\u3001\u901a\u8fc7ID\u83b7\u53d6\u5143\u7d20<\/h2>\n<\/p>\n

JavaScript\u63d0\u4f9b\u7684document.getElementById()<\/code>\u65b9\u6cd5\u662f\u6700\u5feb\u6377\u7684\u83b7\u53d6\u5177\u6709\u7279\u5b9aID\u7684DOM\u5143\u7d20\u7684\u65b9\u6cd5\u3002\u6bcf\u4e2aHTML\u5143\u7d20\u90fd\u53ef\u4ee5\u6709\u4e00\u4e2aID\u5c5e\u6027\uff0c\u8be5\u5c5e\u6027\u5728\u6574\u4e2a\u6587\u6863\u4e2d\u5e94\u8be5\u662f\u552f\u4e00\u7684\u3002<\/p>\n<\/p>\n

let element = document.getElementById('myElement');<\/p>\n
<\/code><\/pre>\n<\/p>\n
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\u4e8c\u3001\u901a\u8fc7\u7c7b\u540d\u6216\u6807\u7b7e\u540d\u83b7\u53d6\u5143\u7d20<\/h2>\n<\/p>\n
\u5f53\u9700\u8981\u83b7\u53d6\u5177\u6709\u7279\u5b9a\u7c7b\u540d\u7684\u6240\u6709\u5143\u7d20\u65f6\uff0cdocument.getElementsByClassName()<\/code>\u65b9\u6cd5\u63d0\u4f9b\u4e86\u4e00\u4e2a\u4fbf\u6377\u7684\u63a5\u53e3\u3002<\/p>\n<\/p>\n
let elements = document.getElementsByClassName('myClass');<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u4e0e\u4e4b\u7c7b\u4f3c\uff0cdocument.getElementsByTagName()<\/code>\u5141\u8bb8\u5f00\u53d1\u8005\u83b7\u53d6\u5177\u6709\u7279\u5b9a\u6807\u7b7e\u540d\u7684\u6240\u6709\u5143\u7d20\uff0c\u5982\u6240\u6709\u7684<div><\/code>\u6216<a><\/code>\u5143\u7d20\u3002<\/p>\n<\/p>\n
let elements = document.getElementsByTagName('div');<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u8fd9\u4e24\u79cd\u65b9\u6cd5\u90fd\u8fd4\u56de\u4e00\u4e2aHTMLCollection\uff0c\u7c7b\u4f3c\u4e8e\u6570\u7ec4\u4f46\u6709\u4e9b\u4e0d\u540c\uff0c\u5b83\u662f\u4e00\u4e2a\u52a8\u6001\u7684\u96c6\u5408\uff0c\u610f\u5473\u7740\u5982\u679cDOM\u4e2d\u7684\u5143\u7d20\u6539\u53d8\uff0c\u8fd9\u4e2a\u96c6\u5408\u4e5f\u4f1a\u76f8\u5e94\u5730\u66f4\u65b0\u3002<\/p>\n<\/p>\n
\u4e09\u3001\u4f7f\u7528CSS\u9009\u62e9\u5668<\/h2>\n<\/p>\n
document.querySelector()<\/code>\u548cdocument.querySelectorAll()<\/code>\u65b9\u6cd5\u5141\u8bb8\u4f7f\u7528CSS\u9009\u62e9\u5668\u4f5c\u4e3a\u53c2\u6570\uff0c\u8fd9\u63d0\u4f9b\u4e86\u6781\u5927\u7684\u7075\u6d3b\u6027\u548c\u5f3a\u5927\u7684\u529f\u80fd\u3002<\/p>\n<\/p>\n
let element = document.querySelector('.myClass');<\/p>\n
let elements = document.querySelectorAll('div.myClass');<\/p>\n
<\/code><\/pre>\n<\/p>\n
document.querySelector()<\/code>\u8fd4\u56de\u6587\u6863\u4e2d\u5339\u914d\u6307\u5b9aCSS\u9009\u62e9\u5668\u7684\u7b2c\u4e00\u4e2a\u5143\u7d20\u3002\u800cdocument.querySelectorAll()<\/code>\u5219\u8fd4\u56de\u6240\u6709\u5339\u914d\u7684\u5143\u7d20\u96c6\u5408\uff0c\u5373\u4f7f\u53ea\u627e\u5230\u4e00\u4e2a\u5339\u914d\u9879\uff0c\u4e5f\u4f1a\u8fd4\u56de\u4e00\u4e2aNodeList\u5bf9\u8c61\u3002<\/p>\n<\/p>\n
\u56db\u3001\u6bd4\u8f83\u548c\u9009\u62e9\u65b9\u6cd5<\/h2>\n<\/p>\n
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\u4e94\u3001\u5b9e\u8df5\u5efa\u8bae\u4e0e\u6027\u80fd\u8003\u8651<\/h2>\n<\/p>\n
\u5728\u5b9e\u9645\u5f00\u53d1\u4e2d\uff0c\u9009\u62e9\u6b63\u786e\u7684\u65b9\u6cd5\u6765\u83b7\u53d6DOM\u8282\u70b9\u4e0d\u4ec5\u5173\u7cfb\u5230\u4ee3\u7801\u7684\u6e05\u6670\u5ea6\uff0c\u8fd8\u76f4\u63a5\u5f71\u54cd\u5230\u5e94\u7528\u7684\u6027\u80fd\u3002\u9891\u7e41\u64cd\u4f5cDOM\u662fWeb\u5e94\u7528\u4e2d\u6027\u80fd\u74f6\u9888\u7684\u5e38\u89c1\u539f\u56e0\u4e4b\u4e00\u3002\u56e0\u6b64\uff0c\u5efa\u8bae\u5f00\u53d1\u8005\u5728\u8fdb\u884cDOM\u64cd\u4f5c\u65f6\u5145\u5206\u8003\u8651\u5176\u5bf9\u6027\u80fd\u7684\u5f71\u54cd\u3002<\/p>\n<\/p>\n
\u4e00\u79cd\u63d0\u9ad8\u6027\u80fd\u7684\u7b56\u7565\u662f\u5c3d\u91cf\u51cf\u5c11\u8bbf\u95eeDOM\u7684\u6b21\u6570\uff0c\u4f8b\u5982\u901a\u8fc7\u4e00\u6b21\u8c03\u7528document.querySelectorAll()<\/code>\u83b7\u53d6\u6240\u6709\u6240\u9700\u5143\u7d20\uff0c\u5b58\u50a8\u5728\u53d8\u91cf\u4e2d\uff0c\u7136\u540e\u5bf9\u8fd9\u4e9b\u5143\u7d20\u8fdb\u884c\u64cd\u4f5c\uff0c\u800c\u975e\u6bcf\u6b21\u64cd\u4f5c\u65f6\u90fd\u91cd\u65b0\u67e5\u8be2DOM\u3002<\/p>\n<\/p>\n
\u6b64\u5916\uff0c\u5f53\u4f7f\u7528\u5982document.getElementById()<\/code>\u8fd9\u7c7b\u65b9\u6cd5\u65f6\uff0c\u7531\u4e8eDOM\u7684\u7ed3\u6784\u53ef\u80fd\u4f1a\u53d1\u751f\u6539\u53d8\uff0c\u5e94\u6ce8\u610f\u786e\u4fdd\u5728\u4f7f\u7528\u83b7\u53d6\u5230\u7684\u5143\u7d20\u524d\uff0c\u8be5\u5143\u7d20\u786e\u5b9e\u5b58\u5728\u4e8eDOM\u4e2d\u3002<\/p>\n<\/p>\n
\u603b\u4e4b\uff0c\u5f00\u53d1\u8005\u5e94\u6839\u636e\u5177\u4f53\u60c5\u51b5\uff0c\u7efc\u5408\u8003\u8651\u6027\u80fd\u3001\u53ef\u8bfb\u6027\u4ee5\u53ca\u4ee3\u7801\u7684\u7ef4\u62a4\u6027\uff0c\u9009\u62e9\u6700\u9002\u5408\u5f53\u524d\u9700\u6c42\u7684\u65b9\u6cd5\u6765\u83b7\u53d6\u548c\u64cd\u4f5cDOM\u8282\u70b9\u3002<\/p>\n<\/p>\n
\u76f8\u5173\u95ee\u7b54FAQs\uff1a<\/strong><\/h2>\n
1. \u5982\u4f55\u4f7f\u7528 JavaScript \u83b7\u53d6 HTML \u4e2d\u7684 DOM \u8282\u70b9\uff1f<\/strong>
\n\u5728 JavaScript \u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528document.getElementById()<\/code>\u65b9\u6cd5\u6765\u83b7\u53d6\u6307\u5b9aid\u7684\u5143\u7d20\u8282\u70b9\u3002\u4f8b\u5982\uff0c\u5982\u679c\u4f60\u8981\u83b7\u53d6id\u4e3a"myElement"\u7684\u5143\u7d20\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u4ee3\u7801\uff1a<\/p>\n
var element = document.getElementById("myElement");\n<\/code><\/pre>\n
\u4f60\u4e5f\u53ef\u4ee5\u4f7f\u7528document.getElementsByClassName()<\/code>\u6216document.getElementsByTagName()<\/code>\u65b9\u6cd5\u6765\u83b7\u53d6\u7c7b\u540d\u6216\u6807\u7b7e\u540d\u5339\u914d\u7684\u5143\u7d20\u8282\u70b9\u3002<\/p>\n
2. \u9664\u4e86\u901a\u8fc7id\u3001\u7c7b\u540d\u548c\u6807\u7b7e\u540d\u83b7\u53d6\u5143\u7d20\u8282\u70b9\u5916\uff0c\u8fd8\u6709\u5176\u4ed6\u65b9\u6cd5\u5417\uff1f<\/strong>
\n\u662f\u7684\uff0c\u9664\u4e86\u4e0a\u8ff0\u65b9\u6cd5\uff0c\u8fd8\u6709\u5176\u4ed6\u65b9\u6cd5\u6765\u83b7\u53d6 HTML \u4e2d\u7684 DOM \u8282\u70b9\u3002\u4f8b\u5982\uff0c\u4f60\u53ef\u4ee5\u4f7f\u7528document.querySelector()<\/code>\u65b9\u6cd5\u6765\u901a\u8fc7 CSS \u9009\u62e9\u5668\u6765\u83b7\u53d6\u5339\u914d\u7684\u7b2c\u4e00\u4e2a\u5143\u7d20\u8282\u70b9\uff0c\u4f7f\u7528document.querySelectorAll()<\/code>\u65b9\u6cd5\u6765\u83b7\u53d6\u6240\u6709\u5339\u914d\u7684\u5143\u7d20\u8282\u70b9\uff0c\u4f8b\u5982\uff1a<\/p>\n
var firstElement = document.querySelector("#myElement"); \/\/ \u901a\u8fc7id\u83b7\u53d6\u7b2c\u4e00\u4e2a\u5339\u914d\u7684\u5143\u7d20\nvar allElements = document.querySelectorAll(".myClass"); \/\/ \u901a\u8fc7\u7c7b\u540d\u83b7\u53d6\u6240\u6709\u5339\u914d\u7684\u5143\u7d20\n<\/code><\/pre>\n
\u8fd9\u4e9b\u65b9\u6cd5\u53ef\u6839\u636e\u9700\u8981\u66f4\u7075\u6d3b\u5730\u9009\u62e9\u9700\u8981\u7684\u5143\u7d20\u8282\u70b9\u3002<\/p>\n
3. \u5982\u4f55\u5728 JavaScript \u4e2d\u904d\u5386 HTML DOM \u8282\u70b9\uff1f<\/strong>
\n\u5728 JavaScript \u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u5faa\u73af\u7ed3\u6784\u6765\u904d\u5386 DOM \u8282\u70b9\u3002\u4f8b\u5982\uff0c\u4f60\u53ef\u4ee5\u4f7f\u7528for<\/code>\u5faa\u73af\u6765\u904d\u5386\u901a\u8fc7\u7c7b\u540d\u83b7\u53d6\u7684\u5143\u7d20\u8282\u70b9\uff0c\u4f7f\u7528forEach<\/code>\u65b9\u6cd5\u6765\u904d\u5386\u901a\u8fc7CSS\u9009\u62e9\u5668\u83b7\u53d6\u7684\u591a\u4e2a\u5143\u7d20\u8282\u70b9\uff0c\u4f8b\u5982\uff1a<\/p>\n
var elements = document.getElementsByClassName("myClass");\nfor (var i = 0; i < elements.length; i++) {\n  console.log(elements[i].innerText);\n}\n\nvar allElements = document.querySelectorAll(".myClass");\nallElements.forEach(function(element) {\n  console.log(element.innerText);\n});\n<\/code><\/pre>\n
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