检查id是否已经存在

How can I check if an html tag with its unique id exists twice or more times ?

如何检查具有惟一id的html标记是否存在两次或多次?

my pseudocode:

我的伪代码:

if($('#myId') > 1) {
  // exists twice
}

4 个解决方案

#1

ID selector only catches the first element which is first in the page. So the length of ID selector should be 0 or 1 always.

ID选择器只捕获页面中第一个元素。所以ID选择器的长度应该是0或1。

So use attribute equals selector instead and check it's length.

使用属性= selector来检查它的长度。

if($('[id="myId"]').length > 1) {
  // exists twice
}

if ($('[id="myId"]').length > 1) {
  console.log('twice');
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="myId"></div>
<div id="myId"></div>

#2

JQuery

if($("[id=someId]").length > 1) {
    //Do Something
}

or

或

if($("[id=someId]").size() > 1) {
    //Do Something
}

Javascript

if(document.querySelectorAll("[id=someId]").length > 1) {
    //Do Something
}

#3

if($("[id='myId']").length > 1) {
    // write your code here
}

#4

This is too simple you might get from small search

这太简单了，你可以从小搜索中得到

if($("#" + name).length > 1) {
  // if exists twice 
}

how many time it exists = $("#" + name).length

它存在的时间= $("#" + name).length