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SyntaxError: for-in loop head declarations may not have initializers

    SyntaxError: for-in loop head declarations cannot have an initializer (Edge)
    SyntaxError: for-in loop head declarations may not have initializers (Firefox)
    SyntaxError: for-in loop variable declaration may not have an initializer. (Chrome)

In this article

(Strict) SyntaxError.

?

for...in . , |for (var i = 0 in obj)| . (non-strict) |for (var i in obj)| . SyntaxError .

SyntaxError .

js
const obj = { a: 1, b: 2, c: 3 };

for (const i = 0 in obj) {
  console.log(obj[i]);
}

// SyntaxError: for-in loop head declarations may not have initializers

for-in

for-in (i = 0) .

js
"use strict";

var obj = { a: 1, b: 2, c: 3 };

for (var i in obj) {
  console.log(obj[i]);
}

for...in . (Array) for-in for ? for :

js
var arr = ["a", "b", "c"];

for (var i = 2; i < arr.length; i++) {
  console.log(arr[i]);
}

// "c"

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