JS: Array.prototype.entries

By Xah Lee. Date: . Last updated: .

(new in ECMAScript 2015)

xArray.entries()
  • Return a Generator.
  • Each yield is an array of the form [index, value].
console.log(["a", "b", "c"].entries());
// Object [Array Iterator] {}

console.log(Array.from(["a", "b", "c"].entries()));
// [ [ 0, "a" ], [ 1, "b" ], [ 2, "c" ] ]

Example. Convert array to map with index as keys

// convert array to map
console.log((new Map(Array.from(["a", "b", "c"].entries()))));
// Map(3) { 0 => "a", 1 => "b", 2 => "c" }

Array Iterator