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SyntaxError: for-of loop head declarations cannot have an initializer (Edge)
SyntaxError: a declaration in the head of a for-of loop can't have an initializer (Firefox)
SyntaxError: for-of loop variable declaration may not have an initializer. (Chrome)

SyntaxError

for...of |for (var i = 0 of iterable)| for-of for

`for-of`

let iterable = [10, 20, 30];

for (let value = 50 of iterable) {
  console.log(value);
}

// SyntaxError: a declaration in the head of a for-of loop can't
// have an initializer

`for-of`

for-of (value = 50) 50 50

let iterable = [10, 20, 30];

for (let value of iterable) {
  value += 50;
  console.log(value);
}
// 60
// 70
// 80

for...of
for...in strict (SyntaxError: for-in loop head declarations may not have initializers)
for

MDN

MDN 2026217

GitHub

JavaScript
JavaScript
1. (+)
2. (+=)
3. (=)
4. async function
5. async function*
6. await
7. (&)
8. (&=)
9. (~)
10. (|)
11. (|=)
12. (^)
13. (^=)
14. class
15. (,)
17. (--)
18. delete
20. (/)
21. (/=)
22. (==)
23. (**)
24. (**=)
25. function
26. function*
27. (>)
28. (>=)
29. ( )
30. import.meta
  1. import.meta.resolve()
31. import()
32. in
33. (++)
34. (!=)
35. instanceof
36. (<<)
37. (<<=)
38. (<)
39. (<=)
40. (&&)
41. (&&=)
42. (!)
43. (||)
44. (||=)
45. (*)
46. (*=)
47. new
48. new.target
49. null
50. (??=)
51. (??)
54. (?.)
56. (%)
57. (%=)
58. (>>)
59. (>>=)
60. (...)
61. (===)
62. (!==)
63. (-)
64. (-=)
65. super
66. this
67. typeof
68. (-)
69. (+)
70. (>>>)
71. (>>>=)
72. void
73. yield
74. yield*