JavaScript .indexOf()

Searches a string for a given value and returns the first index if found. Returns -1 if not found.

Syntax

string.indexOf(value, startSearch);

• value is the value to search for in a string.
• startSearch (optional), indicates the index to start the search at.

Examples

Find the index of string:

const gingerbreadRhyme = `You can't catch me! I'm the Gingerbread Man!`;

const captureGingerbreadMan = gingerbreadRhyme.indexOf('Gingerbread Man');

console.log(captureGingerbreadMan);
// Output: 28

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Find the first occurrence of a string:

const baseballChant =
  'Hey batter, batter, batter, batter, batter! Swing, batter!';

const firstBatter = baseballChant.indexOf('batter');

console.log(firstBatter);
// Output: 4

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Use second parameter to start search later in string:

const baseballChant =
  'Hey batter, batter, batter, batter, batter! Swing, batter!';

const latterBatter = baseballChant.indexOf('batter', 18);

console.log(latterBatter);
// Output: 20

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Return -1 if not found:

const people = ['Dominic', 'Marshawn', 'Alexis', 'Shannon'];

const didYouFindWaldo = people.indexOf('Waldo');

console.log(didYouFindWaldo);
// Output: -1

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Codebyte Example

The following is runnable, and demonstrates the use of the .indexOf() method:

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