- Categories: JavaScript Methods, JavaScript Reference, Reference
Quick Reference
The String indexOf() method returns the position of the first occurrence of a value in a string, and returns -1 if the value is not found. The indexOf() method is case sensitive.
<!-- html element to place output -->
<p id="my_output"></p>
Example 1
// variables
let text = 'Hello World';
let my_value = text.indexOf('W'); // search entire string
// output to the HTML element
document.getElementById('my_output').innerHTML = my_value;
Example 2
// variables
let text = 'Hello World';
let my_value = text.indexOf('W', 3); // search string starting at position 3
// output to the HTML element
document.getElementById('my_output').innerHTML = my_value;
Output
Example 1
6
Example 2
6
Syntax
string.includes(searchvalue, start)
Parameters
| Parameter | Description |
|---|---|
| searchvalue | The string to search for (required) |
| start | The position to start from (default value is 0) |
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JAVASCRIPT NOTES:
- When using JavaScript, single or double quotation marks are acceptable and work identically to one another; choose whichever you prefer, and stay consistent
- JavaScript is a case-sensitive language; firstName is NOT the same as firstname
- Arrays count starting from zero NOT one; so item 1 is position [0], item 2 is position [1], and item 3 is position [2] … and so on
- JavaScript variables must begin with a letter, $, or _
- JavaScript variables are case sensitive (x is not the same as X)
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