Detailed explanation of commonly used DOM methods in js
Introducing several common methods of js DOM
Get element nodes getElementById getElementsByTagName getElementsByClassName
First write a simple web page for testing:
/* test.html */ <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>test</title> </head> <body> <p id="contentId" style="width:500px; height: 30px;background-color: #ccc">这段的id是contentId。</p> <p class="contentClass" style="width:500px; height: 30px;background-color: #ccc">这段的class name是contentClass。</p> </body> </html>
1. getElementById
1. First define the variable var contentId = document.getElementById("contentId");
2. Then output the object contentId and return the element object with the id contentId (
). See the picture below:
2. getElementsByTagName
1. Define the variable first var contentTag = document.getElementsByTagName("p");
2. Then I output the contentTag, which returns two HTMLCollection [
3. Continue contentTag[0] Output
contentTag[ 1] Output
##After changing the style attribute:
5. Then this is childNOdes:
##That is to say,
When encountering block elements, there will be There is a newline character, and the browser will treat it as a text node when looking for child nodes. It can also be seen from the figure that childNodes also returns an array.
What if it is There are 12 types of nodeType values, and there are three commonly used ones: 1 represents element node, 2 represents attribute node, and 3 represents text node. 
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