Jul 26, 2024 · The contains() method of the Node interface returns a boolean value indicating whether a node is a descendant of a given node, that is the node itself, one of its direct children (childNodes), one of the children's direct children, and so on.

The includes() method returns true if a string contains a specified string. Otherwise it returns false. The includes() method is case sensitive.

In this tutorial, you will learn how to use the JavaScript contains() method to check if a node is a descendant of a given node.

Location objects have a toString method returning the current URL. You can also assign a string to window.location. This means that you can work with window.location as if it were a string in most cases. Sometimes, for example when you need to call a String method on it, you have to explicitly call toString.

Nov 24, 2009 · ECMAScript 6 introduced String.prototype.includes: String.prototype.includes is case-sensitive and is not supported by Internet Explorer without a polyfill. In ECMAScript 5 or older environments, use String.prototype.indexOf, which returns -1 …

Mar 13, 2025 · The includes() method of String values performs a case-sensitive search to determine whether a given string may be found within this string, returning true or false as appropriate. const sentence = "The quick brown fox jumps over the lazy dog."; A string to be searched for within str. Cannot be a regex.

Feb 10, 2010 · How can I check if one DOM element is a child of another DOM element? Are there any built in methods for this? For example, something like this to check if element2 is contained within element1: Or if element2 has element1 as a parent/grandparent/etc: If not then any ideas how to do this? It also needs to be cross-browser compatible.

Apr 6, 2022 · The contains() method is used to check whether or not a collection contains a specific item. If the item is present, it returns true; otherwise, it returns false. The function is applied to the collection once the JavaScript array is turned into a collection.

What Does .includes() Do in JavaScript? The .includes() method allows you to check if a string contains another substring within it. For example: let str = "Hello world!"; Here, we check if str contains the word "world" inside it. Since "world" exists in …

Nov 5, 2021 · In JavaScript you can use the .includes() method to see if one string is found in another. Here is the basic syntax for the .includes() method. If the search-string is found then it will return true. If the search-string is not found then it will return false.