have file_name.JSON, like
[{"id": 1},{"id": 2},{"id": 3}]
How can I use "for" to get in final: 1,2,3
const file_name = [{
"id": 1
}, {
"id": 2
}, {
"id": 3
}]
for (let i = 0; i <= file_name.length; i++) {
console.log(file_name[i].id);
}Or maybe another way, not use "for"
To fix your code you need just to change i <= file_name.length to i < file_name.length
const file_name = [{
"id": 1
}, {
"id": 2
}, {
"id": 3
}]
for (let i = 0; i < file_name.length; i++) {
console.log(file_name[i].id);
}Or for a better and clean code you can use map
const file_name = [{
"id": 1
}, {
"id": 2
}, {
"id": 3
}]
const res = file_name.map(({
id
}) => console.log(id));Use map
const file_name = [{
"id": 1
}, {
"id": 2
}, {
"id": 3
}]
let arr = file_name.map(e => e.id);
console.log(arr);
let str = file_name.map(e => e.id).join();
console.log(str);
No, you don't have JSON, you have a plain old Javascript array there.
var file_name = [{"id": 1},{"id": 2},{"id": 3}];
var justNumbers = file_name.map(e => e.id);
console.log(justNumbers);
id of undefinederror. Are you asking about the usage of the loop or how to fetch the file?