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JavaScript indexOf() Method
JavaScript String Object
Definition and Usage
The indexOf() method returns the position of the first occurrence of a specified value in a string.
This method returns -1 if the value to search for never occurs.
Syntax
string.indexOf(searchstring, start)
| Parameter | Description |
|---|---|
| searchstring | Required. The string to search for |
| start | Optional. The start position in the string to start the search. If omitted, the search starts from position 0 |
Browser Support
The indexOf() method is supported in all major browsers.
Tips and Notes
Note: The indexOf() method is case sensitive!
Tip: Also look at the lastIndexOf() method.
Examples
Example 1
Do different searches within a string:
<script type="text/javascript">
var str="Hello world!";
document.write(str.indexOf("d") + "<br />");
document.write(str.indexOf("WORLD") + "<br />");
document.write(str.indexOf("world"));
</script>
var str="Hello world!";
document.write(str.indexOf("d") + "<br />");
document.write(str.indexOf("WORLD") + "<br />");
document.write(str.indexOf("world"));
</script>
The output of the code above will be:
10
-1
6
-1
6
Try it yourself »
Example 2
Differences between indexOf and lastIndexOf:
<script type="text/javascript">
var str="I love W3Schools!"
document.write("Index of first o: " + str.indexOf("o"))
document.write("<br />")
document.write("Index of last o: " + str.lastIndexOf("o"))
document.write("<br />")
document.write("Index of first 'love': " + str.indexOf("love"))
document.write("<br />")
document.write("Index of last 'love': " + str.lastIndexOf("love"))
</script>
var str="I love W3Schools!"
document.write("Index of first o: " + str.indexOf("o"))
document.write("<br />")
document.write("Index of last o: " + str.lastIndexOf("o"))
document.write("<br />")
document.write("Index of first 'love': " + str.indexOf("love"))
document.write("<br />")
document.write("Index of last 'love': " + str.lastIndexOf("love"))
</script>
The output of the code above will be:
Index of first o: 3
Index of last o: 13
Index of first 'love': 2
Index of last 'love': 2
Index of last o: 13
Index of first 'love': 2
Index of last 'love': 2
Try it yourself »
JavaScript String Object
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Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content.
While using this site, you agree to have read and accepted our terms of use and privacy policy.
Copyright 1999-2012 by Refsnes Data. All Rights Reserved.
Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content.
While using this site, you agree to have read and accepted our terms of use and privacy policy.
Copyright 1999-2012 by Refsnes Data. All Rights Reserved.