JavaScript lastIndexOf() string method is used to get the last occurrence of a substring in a string. It searches the position of a particular character or string in a sequence of given char values.
lastIndexOf(searchString)
lastIndexOf(searchString, position)
This method returns the index (position) of the last occurrence of a specified value in a string. And returns -1 if the value is not found.
Note: This method is case-sensitive.
JavaScript lastIndexOf()
Simple example code.
<!DOCTYPE html>
<html>
<body>
<script>
let text = "Mr. Green has a green Mouse";
let res = text.lastIndexOf("green");
console.log(res)
// case sensitive
let out = text.lastIndexOf("Green");
console.log(out)
</script>
</body>
</html>Output:
If you pass the fromIndex the argument to the string, the lastIndexOf() method will start searching backward from the fromIndex as shown in the following example:
let str = 'JavaScript';
let index = str.lastIndexOf('a',2);
console.log(index);//1When Substring Is Not Found
var str = "I love JavaScript";
// passing a substring that is not in a given string
var result = str.lastIndexOf("Python")
console.log(result); //-1These are the following ways used to search for the position of an element.
| Method | Description |
|---|---|
| lastIndexOf(ch) | It returns the last index position of the char value passed with the method. |
| lastIndexOf(ch,index) | It starts searching the element from the provided index value in the inverse order and then returns the index position of the specified char value. |
| lastIndexOf(str) | It returns the index position of the first character of the string passed with the method. |
| lastIndexOf(str,index) | It starts searching the element from the provided index value and then returns the index position of the first character of a string. |
Do comment if you have any doubts or suggestions on this Js string method tutorial.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version