JS: for-of Loop

for-of Loop

The for-of loop is a syntax that lets you loop over Iterable Object's items.

for (variable of iterable) {body}

Example: Loop Over Array

for-of loop on Array

for (let x of [3, 4, 5]) {
  console.log(x);
}
/*
3
4
5
*/

Example: Loop Over Array with Index and Value

Go over array with index and value. By Destructuring Assignment and Array.prototype.entries.

let xx = ["a", "b", "c"];

/* loop over array with index and value */
for (let [i, v] of xx.entries()) {
  console.log(i, v);
}

/*
prints
0 a
1 b
2 c
*/

Example: Loop Over Characters in String

When used on string, it goes thru each char, not String Code Unit . This fixed a long time JavaScript problem.

/* iterate characters in string, by for-of loop. */
for (let x of "ab🦋d") { console.log(x);}
/*
a
b
🦋
d
*/

Example: Loop Over Set Object

〔see JS: the Set Object Tutorial〕

/* for-of loop over set object */
let xx = new Set([3, 4, 5]);

for (let v of xx) {
  console.log(v);
}

/*
prints
3
4
5
*/

Loop Over Map Object

• JS: Iterate Map Object