Array.findIndex

findIndex — Executes a provided function once per array element. If the function returns a true value, it will break the loop and return that index.

Description

Array.findIndex(function callback, [object this])

Parameters

Return values

integer. Returns the index of the found element or -1 if not found.

Changelog

Examples

Example #1 – findIndex example

Run
var array = [2, 4, 8];

var result = array.findIndex(function () {
	console.log(this);
	return true;
});

console.log(result);  // 0

Run
var arr = [2, 4, 8];

var result = arr.findIndex(function (value, index, array) {
	console.log(value, index, array);
	return true;
});

console.log(result);  // 0

Passing in a custom object for this.

Run
var array = [2, 4, 8];

var result = array.findIndex(function () {
	console.log(this);
	return true;
}, document.location);

console.log(result);  // 0

Emulates a failed test when the value 2 is discovered. This will make it go to the next iteration.

Run
var array = [2, 4, 4, 8];

var result = array.findIndex(function (value) {
	if (value === 2) {
		return false;
	}
	return true;
});

console.log(result);  // 1

And if all tests fail.

Run
var array = [2, 4, 8];

var result = array.findIndex(function (value) {
	console.log(value);
	return false;
});

console.log(result);  // -1

External references

• Mozilla: Array.findIndex method