_.indexOf

Returns the first index at which a given element can be found in the array, or -1 if it is not present.

// Underscore/Lodash
var array = [2, 9, 9]
var result = _.indexOf(array, 2)
console.log(result)
// output: 0
 
// Native
var array = [2, 9, 9]
var result = array.indexOf(2)
console.log(result)
// output: 0

Browser Support for Array.prototype.indexOf()

✔	✔	1.5 ✔	9.0 ✔	✔	✔