JavaScript - String indexOf() method example

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// ONLINE-RUNNER:browser;

const text = 'ABCABC';

console.log(text.indexOf('A')); // 0
console.log(text.indexOf('B')); // 1
console.log(text.indexOf('C')); // 2

console.log(text.indexOf('A', 3)); // 3
console.log(text.indexOf('B', 3)); // 4
console.log(text.indexOf('C', 3)); // 5

console.log(text.indexOf('BC'));    // 1
console.log(text.indexOf('BC', 3)); // 4

console.log(text.indexOf('123'));    // -1
console.log(text.indexOf('123', 2)); // -1

1. Documentation


String indexOf(searchString)

String indexOf(searchString, position)


searchString - a substring to search for.

position - a position to search from.


The method returns the index of the first occurrence of searchString or -1 if not found.

If the method is called with no arguments returns 0.


The method searches the entire calling string and returns the index of the first occurrence of the specified substring.

If the second argument is given, the method returns the first occurrence of the specified substring at an index greater than or equal to the specified number.

See also

  1. JavaScript - get index of item in array

  2. JavaScript - index of text in string after indicated position


  1. String.prototype.indexOf() - JavaScript | MDN

Alternative titles

  1. JavaScript - String.indexOf() documentation with examples
  2. js - String indexOf() method documentation with examples
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JavaScript - String (documentation)

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