JavaScript String indexOf() Method

indexOf()Returns the position of the first occurrence of the specified value in the string.

If the value is not found, it will return-1.

If the value exists multiple times, it will return the position of the first occurrence.

If you want to search from the beginning, uselastIndexOf()method.

Note:For more information on Array methods, seeArray.indexOf().

Syntax:

string.indexOf(searchValue, start)

Example

var str = 'Air Pollution is the introduction of chemicals to the atmosphere';
str.indexOf('Pollution');//　4

Note:This method is case-sensitive.

All browsers fully support the indexOf() method:

Method
indexOf()	Is	Is	Is	Is	Is

Parameter	Description
searchValue	(Required) A string representing the value to search for
start	(Optional) An integer representing the index at which to start the search; the default is 0

Return value:	first occurrencesearchValueindex, if not found then-1
JavaScript version:	ECMAScript 1

Return the position of the character 'L' in the string, starting from position6Start searching:

Example

var str = 'HELLO WORLD HELLO';
str.indexOf('L',　6);