Use for-of-loop for questions related to the for...of statement used for iterating over an iterable collection.
References
Questions tagged [for-of-loop]
157 questions
437
votes
12 answers
Access to ES6 array element index inside for-of loop
We can access array elements using a for-of loop:
for (const j of [1, 2, 3, 4, 5]) {
console.log(j);
}
How can I modify this code to access the current index too? I want to achieve this using for-of syntax, neither forEach nor for-in.
Abdennour TOUMI
- 87,526
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66
votes
4 answers
for...of loop. Should I use const or let?
When using a for of loop, both of these are allowed and work:
const numbers = [1,2,3];
// works
for(let number of numbers) {
console.log(number);
}
// also works
for(const number of numbers) {
console.log(number);
}
I always use const since…
Tomáš Zato
- 50,171
- 52
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- 778
60
votes
2 answers
How can I turn off ESLint's no-restricted-syntax rule just for ForOfStatement?
I am using ESLint for my ES6 program, with the AirBNB rule-set. For good and adequate reasons, I am using the for...of construction in my code, but ESLint objects to it, issuing a no-restricted-syntax error.
The documentation at…
Mike Taylor
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36
votes
1 answer
Can I use continue and break in Javascript for...in and for...of loops?
Can I use the break and continue statements inside the for...in and for...of type of loops? Or are they only accessible inside regular for loops.
Example:
myObject = {
propA: 'foo',
propB: 'bar'
};
for (let propName in myObject) {
if…
cbdeveloper
- 27,898
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- 336
27
votes
4 answers
How to iterate over a Set or Map in reverse order in javascript?
I'm looking for a a way to iterate over a Set or Map in reverse order.
Consider this simple example in regular order:
var mySet = new Set([1,2,3,4,5]);
for(let myNum of mySet) {
console.log(myNum); // output: 1, 2, 3, 4, 5 in sepearte lines
}
The…
Holger Stitz
- 2,011
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20
votes
3 answers
How can a Javascript object become iterable with for...of statement?
I would like to set the options[Symbol.iterator] property in order to iterate on the simple objects I create with the for...of statement :
options = {
male: 'John',
female: 'Gina',
rel: 'Love'
};
for(let p of options){
…
cicciosgamino
- 871
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- 29
19
votes
5 answers
Type 'HTMLCollectionOf' must have a '[Symbol.iterator]()' method that returns an iterator
I am building an Array with
const myCanvas = document.getElementsByTagName('canvas')
that it's actually working. It returns me something like this:
images: [
0: canvas,
1: canvas,
2: canvas
]
This is for a TypeScript project, I want to…
Jgascona
- 1,201
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18
votes
2 answers
The meaning of "'x' is not a function or its return value is not iterable" error
I accidentally witnessed that this causes an error in V8 (Chrome, Node.js, etc):
for (let val of Symbol()) { /*...*/ }
TypeError: Symbol is not a function or its return value is not iterable
It appears that any other non-iterable value (including…
Estus Flask
- 206,104
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11
votes
3 answers
Remove array item using for...of loop
I'm trying to edit an array and remove elements that do not meet a certain condition. If I use a reverse for loop combined with .splice(index,n), the code works just fine. I'm stuck at implementing the same using the ES6 for...of loop
let…
danieln
- 473
- 1
- 5
- 20
10
votes
2 answers
for..in or for..of Object keys
So my IDE doesn't like when I use a for..in loop to iterate over an object keys. I get a warning:
Possible iteration over unexpected (custom / inherited) members, probably missing hasOwnProperty check
So I get what it's saying, so in that case…
Spedwards
- 4,167
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- 106
9
votes
2 answers
What is the difference between iterable and enumerable in JS? I am going through For/of and For/In loop and these terms are coming up frequently
I am coming across terms Iterable and Enumerable while studying For/in and For/of loops. Objects are supposed be enumerable and we have to use For/in loop to loop over the properties of the object and For/of to loop over the arrays and strings. I…
Mahwash
- 91
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- 4
7
votes
2 answers
For-Of Loop vs. For Loop
Are these two the same or interchangeable?
What are some use cases that someone would choose one over the other?
for(let i of array){some code}
for(let i = 0; i < array.length; i++){some code}
EXAMPLE
Complete the solution so that the function…
and1
- 307
- 2
- 10
6
votes
1 answer
for...of an iterator without closing it
Is it possible to loop over part of an iterator with for...of without closing the iterator when I break the loop?
Example:
function* numbers(i=0){
while(true) yield i++;
}
let nums=numbers();
// this loop prints numbers from 0 to 3
for(const n…
Blue Nebula
- 932
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- 9
5
votes
1 answer
In JavaScript, Iterating over generator using for-of loop ignore return statement why?
Take a close look at code
function* NinjaGenerator() {
yield "yoshi";
return "Hattori";
}
for (let ninja of NinjaGenerator()) {
console.log(ninja);
}
// console log : yoshi
Why "Hattori" is not logged ? Where as when we iterate over…
Faizanur Rahman
- 474
- 3
- 12
5
votes
2 answers
How does Break work in for-of loop when stopping a Generator?
So there are some ways to stopping a Generator in for of loop, but how does break send a signal to the Generator(in comparison with return in for-of)?
please consider the code.
As an example, the preceding code just increases a value from 1 to 10…
Mehdi Raash
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