JS judges whether an array contains a certain value

Optional integer parameter. Specifies the position in the string to start searching. Its valid values ​​are 0 to stringObject.length – 1. If this parameter is omitted, the search will start from the first character of the string.

Note: The indexOf() method is case sensitive!

Note: If the string value to be retrieved is not present, the method returns -1.

Specific usage:

First create an html file and add the following code:

Then run the html file in the browser

Finally check the running results, “-1” means that this value does not exist;

Related reference:JS Tutorial

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