Showing only specific fields of javascript object in the array doesn't work

Question

I'm trying to show specific series of specific fields and value inside of the object but it's not working.

var objArray = [
    {id:1, photo:true, bol: true }, {id:2, photo: true, bol:true}
];

result = objArray.map((item) => return {id: item.id, photo: item.photo 
}) // this doesn't work.. why??

Expectd Output

[
    {id:1, photo:true}, {id:2, photo: true}
]

score 4 · Accepted Answer · answered Dec 05 '17 at 05:47

4

You need to make two changes

Remove return statement - arrow functions will implicitly return the expression's evaluated result.
Wrap {} with () so that {} doesn't get treated as a code block, but as an expression.

i.e.

objArray.map((item) => ({id: item.id, photo: item.photo  }));

Demo

var objArray = [{
  id: 1,
  photo: true,
  bol: true
}, {
  id: 2,
  photo: true,
  bol: true
}];

var result = objArray.map((item) => ({
  id: item.id,
  photo: item.photo
}));

console.log(result);

answered Dec 05 '17 at 05:47

gurvinder372

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THANKS!! :) great – hellofanengineer Dec 05 '17 at 05:51
Um can I initialize item's value? For example,,, map((item) => let {id, photo} = item; return ({id, photo}); just some thought :) – hellofanengineer Dec 05 '17 at 05:54
wow I've never seen the expression like a { key, key1 } = item; Thanks... – hellofanengineer Dec 05 '17 at 06:01
@JohnBaek my bad, expression that I just gave above doesn't work. You can try this one though https://stackoverflow.com/questions/25553910/one-liner-to-take-some-properties-from-object-in-es-6 – gurvinder372 Dec 05 '17 at 06:09

score 1 · Answer 2 · answered Dec 05 '17 at 05:57

Create temporary Object;

Iterate through object and if key is not "bol", then push it to temp Object;

finally return the temporary Object

var objArray = [
    {id:1, photo:true, bol: true }, {id:2, photo: true, bol:true}
];


result = objArray.map((item) => {
let tempObj = {}
 Object.keys(item).map((key) => {   
   if(key != "bol") {
      tempObj[key] = item[key]
      
   }     
 })
 return tempObj;
 })
 
 console.log(result)

Showing only specific fields of javascript object in the array doesn't work

2 Answers2