Does JavaScript have collections?-JS Tutorial-php.cn

Does JavaScript have collections?

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Release： 2023-01-07 11:43:48

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There are collections in JavaScript. The HTMLCollection object in JavaScript is an array-like list (collection) of HTML elements. The getElementsByTagName() method returns an HTMLCollection object.

Does JavaScript have collections?

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

There are collections in JavaScript. The HTMLCollection object in JavaScript is an array-like list (collection) of HTML elements. The getElementsByTagName() method returns an HTMLCollection object.

DOM collection in JavaScript:

The length attribute defines the number of elements in the HTMLCollection:

Example:

<!DOCTYPE html>
<html>
<body>

<h1>JavaScript HTML DOM</h1>

<p>Hello World!</p>

<p>Hello China!</p>

<p id="demo"></p>

<script>
var myCollection = document.getElementsByTagName("p");
document.getElementById("demo").innerHTML = 
"此文档包含 " + myCollection.length + " 段文字。";
</script>

</body>
</html>

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Effect:

Does JavaScript have collections?

Explanation of examples:

Create a collection of all

elements

Display the length of the collection

Note:

HTMLCollection is not an array!

HTMLCollection may look like an array, but it is not an array.

You can iterate over a list and reference elements numerically (just like an array).

However, you cannot use array methods such as valueOf(), pop(), push(), or join() on HTMLCollection.

[Recommended learning: javascript advanced tutorial]

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