CODEWITHSUNDEEP
javascriptarraysloopsobject
tester123
tester123

Reputation: 1113

Looping through object and setting as values in second object javascript

I have an array, which need to be the keys in my object. I also have an object with the same keys and a default property, which I need to set as the value to my keys in the object I need to build. I'm stuck at how to loop and set the key/values in the empty object. Thanks!!

myFinalObj starts off as an empty object.

My starting object

var startingObj = {
  'one' : {'default': 1, 'name': 'un'},
  'two' : {'default': 2, 'name': 'deux'},
  'three': {'default': 3, 'name': 'trois'}
}

My Array

var myArray = ['one', 'two', 'three'];

My finished Object

var myFinalObj = {
  'one' : 1,
  'two' : 2,
  'three' : 3
}

Upvotes: 0

Views: 38

Answers (8)

lorefnon
lorefnon

Reputation: 13095

var myFinalObj = myArray.reduce((memo, name) => { 
  memo[name] = startingObj[name].default 
  return memo 
}, {})

Quoting from MDN :

The reduce() method applies a function against an accumulator and each value of the array (from left-to-right) to reduce it to a single value.

Arrow functions are a recent addition to javascript, and if your environment does not support them you can use the more verbose but equivalent : 

 var myFinalObj = myArray.reduce(function(memo, name) { 
  memo[name] = startingObj[name].default 
  return memo 
}, {})

For IE < 9 the reduce function is also not available but you can use the polyfill available in the same MDN article .

Upvotes: 2

user2263572
user2263572

Reputation: 5606

Is this what you're trying to do? Based on your test case listed above it seems to work. 

  var startingObj = {
  'one' : {'default': 1, 'name': 'un'},
  'two' : {'default': 2, 'name': 'deux'},
  'three': {'default': 3, 'name': 'trois'}
}

var myArray = ['one', 'two', 'three'];

var return_Obj = {}

for (var i = 0; i < myArray.length; i++){
    for (var key in startingObj){
        if (key == myArray[i]){
           var val = startingObj[key]['default']
        break
        }

    }
    return_Obj[myArray[i]] = val
}

console.log(return_Obj)

Upvotes: 0

leo.fcx
leo.fcx

Reputation: 6467

Use this simple code:

var myFinalObj = {};
myArray.forEach(function(key){
    myFinalObj[key] = startingObj[key].default;
});
console.log(myFinalObj)

Upvotes: 0

Scott Schwalbe
Scott Schwalbe

Reputation: 430

function buildObj(startObj, keyArr, finalObj) {
  var currKey;
  for (var i = 0; i < keyArr.length; i++) {
    currKey = keyArr[i];
    finalObj[currKey] = startObj[currKey]['default'];
  }
}

var myFinalObj = {};
buildObj(startingObj, myArray, myFinalObj);

Upvotes: 0

jordan
jordan

Reputation: 10722

Try this:

var startingObj = {
  'one' : {'default': 1, 'name': 'un'},
  'two' : {'default': 2, 'name': 'deux'},
  'three': {'default': 3, 'name': 'trois'}
}

var myArray = ['one', 'two', 'three'];

var myFinalObj = {}

for(n in myArray){
    if(startingObj.hasOwnProperty(myArray[n])){
        myFinalObj[myArray[n]] = startingObj[myArray[n]].default
    }
}

Upvotes: 0

Downhillski
Downhillski

Reputation: 2655

Recommend using for(.. in ..) or for (var i=0;i<..;i++) as Array.forEach might not be supported in older browsers.

var myArray = ['one', 'two', 'three'];
var startingObj = {
  'one' : {'default': 1, 'name': 'un'},
  'two' : {'default': 2, 'name': 'deux'},
  'three': {'default': 3, 'name': 'trois'}
}
var myFinalObj = {};
for (key in myArray) {
	myFinalObj[myArray[key]] = startingObj[myArray[key]].default;
}
console.log(myFinalObj);

Upvotes: 0

Matthew
Matthew

Reputation: 4339

You can set property keys using obj["key"]=value syntax, so this should work:

var myFinalObject={};
for(var i=0;i<myArray.length;i++){
    myFinalObj[myArray[i]]=startingObj[myArray[i]];
}

Upvotes: 0

Patrick Steadman
Patrick Steadman

Reputation: 738

var startingObj = {
  'one': {
    'default': 1,
    'name': 'un'
  },
  'two': {
    'default': 2,
    'name': 'deux'
  },
  'three': {
    'default': 3,
    'name': 'trois'
  }
}


var myArray = ['one', 'two', 'three'];

var finalObject = {};

myArray.forEach(function(value){
 finalObject[value] = startingObject[value]['default']; 
}

Upvotes: 0

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