New to javascript and trying to learn! I am trying to map through two array of objects, and if a certain property matches, pull in specific information into an array.

let result;

let arrNames = [{
  name: "A"
}, {
  name: "B"
}, {
  name: "C"
}]

let arrInfo = [{
  name: "A",
  info: "AAA"
}, {
  name: "B",
  info: "BBB"
}, {
  name: "C",
  info: "ccc"
}]

If arrNames.name == arrInfo.name, I would like result to equal arrInfo.info.

What I've tried:

arrNames.map(x => {
if(arrNames.name == arrInfo.name){
   result=arrInfo.info
}

^ This obviously doesn't work -- but I'm wondering if Assign or Filter would be appropriate.

Thanks in advance for your help (apologies that this is probably a dupe)!

New to javascript and trying to learn! I am trying to map through two array of objects, and if a certain property matches, pull in specific information into an array.

let result;

let arrNames = [{
  name: "A"
}, {
  name: "B"
}, {
  name: "C"
}]

let arrInfo = [{
  name: "A",
  info: "AAA"
}, {
  name: "B",
  info: "BBB"
}, {
  name: "C",
  info: "ccc"
}]

If arrNames.name == arrInfo.name, I would like result to equal arrInfo.info.

What I've tried:

arrNames.map(x => {
if(arrNames.name == arrInfo.name){
   result=arrInfo.info
}

^ This obviously doesn't work -- but I'm wondering if Assign or Filter would be appropriate.

Thanks in advance for your help (apologies that this is probably a dupe)!

• javascript
• arrays
• object
• prototypejs
• array.prototype.map

• Don't modify the question when existing answers address your original question. Ask a new question instead (I see that you already did). Rolling back to previous version. – Nikhil Commented Oct 12, 2019 at 14:48

3 Answers 3

You can use find() inside map() to find the element. This finds the element even if they aren't at the same index in both arrays.

Then use filter() to filter any undefined values which will be present if there isn't a match.

var arrNames = [
   {name: "A"},
   {name: "B"},
   {name: "C"}
];

var arrInfo = [
   {name: "A", info: "AAA"},
   {name: "B", info: "BBB"},
   {name: "C", info: "ccc"}
];

let result = arrNames.map(x => {
  item = arrInfo.find(item => item.name === x.name);
  if (item) { 
    return item.info;
  }      
}).filter(item => item !== undefined); // Can also use filter(item => item);

console.log(result);

let result = [];

arrNames = [
   {name: "A"},
   {name: "B"},
   {name: "C"},
]

arrInfo = [
   {name: "A", info: "AAA"},
   {name: "B", info: "BBB"},
   {name: "C", info: "ccc"},
]

result = arrNames.map(function(_, index){
  if(arrNames[index].name === arrInfo[index].name) {
    return arrInfo[index].info
  }
})

You can use map with a condition inside

el.name === arrNames[index].name && el.info

Means:

if (el.name === arrNames[index].name) return el.info

let arrNames = [{
  name: "A"
}, {
  name: "B"
}, {
  name: "C"
}]

let arrInfo = [{
  name: "A",
  info: "AAA"
}, {
  name: "B",
  info: "BBB"
}, {
  name: "C",
  info: "ccc"
}]


const res = arrInfo.map((el, index) => el.name === arrNames[index].name && el.info)

console.log(res)