Item is not defined in a for each loop?

Question

I'm looking at the answer here but when doing:

let users = [{name: 'john', address: '10 king street'}, ....];

users.forEach(item, index, object => {

I get the error:

item is not defined

I need this so I can:

object.splice(index, 1);

your syntax seems wrong. Try `users.forEach((item, index, object) => {` — Chris, Jan 29 '18 at 20:07
You're using `foreach` incorrectly. It's first argument is a function. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach — jpaugh, Jan 29 '18 at 20:08

Rick Hitchcock · Accepted Answer · 2018-01-29T20:15:34.070

9

When passing multiple parameters to an arrow function, enclose them in parentheses:

users.forEach((item, index, object) => { ... }

(See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions#Syntax)

For example, to remove all users named "john," do this:

users.forEach((item, index, object) => {
  if(item.name == 'john') {
    object.splice(index, 1);
  }
});

Snippet:

let users = [
  {name: 'john', address: '10 king street'},
  {name: 'mary', address: '10 queen street'},
  {name: 'john', address: '10 prince street'},
  {name: 'hank', address: '10 duke street'}
];

users.forEach((item, index, object) => {
  if(item.name == 'john') {
    object.splice(index, 1);
  }
});

console.log(JSON.stringify(users));

edited Jan 29 '18 at 20:15

answered Jan 29 '18 at 20:08

Rick Hitchcock

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Thanks, what is the difference between item and object? – panthro Jan 29 '18 at 20:09
1

@panthro read the docs, item is the current iteration's item, object is the entire array – Sterling Archer Jan 29 '18 at 20:10

score 1 · Answer 2 · answered Jan 29 '18 at 20:08

1

you need to put all the params into parenthesis like :

users.forEach((item, index, object) => {

answered Jan 29 '18 at 20:08

andrea06590

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score 1 · Answer 3 · answered Jan 29 '18 at 20:13

You forgot to enclose the parameters to the arrow function in parentheses.

users.forEach(item, index, object => { /* ... */ })

Doing this means you pass to the function item, index, and an arrow function with a single param object(parentheses not needed with a single param). Change to this:

users.forEach((item, index, object) => { /* ... */ })

This will pass an arrow function with 3 params: item is the current item, index - the index, object - the object forEach was called on - in this case users.

Item is not defined in a for each loop?

3 Answers3