Insert an arrays mapping to the index of another array by adding property into array using javascript

Question

Have an array as

result1= [
    [{name:"a",fruit:"apple"},{name:"b",fruit:"banana"}],
    [{name:"o",fruit:"orange"}],
    [{name:"g",fruit:"grapes"},{name:"s",fruit:"strawberries"}]
]

and

result2 =[
    {country:"japan",color:"red"},
    {country:"NewZealand",colour:"yellow"},
    {country:"srilanka",colour:"green"}
]

would need to insert a property having arrays inside the second with the indexes being same...length of the two arrays are same...resulted array should be

result3 = [
    {country:"japan",color:"red",newproperty:"[{name:"a",fruit:"apple"},{name:"b",fruit:"banana"}]"},
    {country:"NewZealand",colour:"yellow",newproperty:"[{name:"o",fruit:"orange"}]"},
    {country:"srilanka",colour:"green",newproperty:"[{name:"g",fruit:"grapes"},{name:"s",fruit:"strawberries"}]"}
]

i have tried with the below code

result3 = (result2.map((o, i) => Object.assign(o, result1[i])))

result of this adding each object of array rather than whole array itself from result1 to result2

Have tried with the code to add a property using map result fluctuates...please help with this

Taki · Accepted Answer · 2018-04-20 18:21:40Z

3

you can use bracket notation to add new property to the object

const result1= [[{name:"a",fruit:"apple"},{name:"b",fruit:"banana"}],[{name:"o",fruit:"orange"}],[{name:"g",fruit:"grapes"},{name:"s",fruit:"strawberries"}]]

const result2 =[{country:"japan",color:"red"},{country:"NewZealand",colour:"yellow"},{country:"srilanka",colour:"green"}]

const result3 = result2.map((e,i) => {
  e['newproperty'] = result1[i];
  return e;
});

console.log(result3)

answered Apr 20, 2018 at 18:21

Taki

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1 Comment

MaxZoom Over a year ago

It is worth to mentioned that the result2 has changed

Nina Scholz · Accepted Answer · 2018-04-20 18:37:28Z

2

You could need an object, not just the array for assigning.

result3 = result2.map((o, i) => Object.assign(    o,                result1[i]  )) // old
result3 = result2.map((o, i) => Object.assign({}, o, { newproperty: result1[i] })) // new
                                              ^^  ^  ^ ^^^^^^^^^^^             ^
                                              new object
                                                  source not target
                                                     object with
                                                        property

For preventing to mutate result2, you need an empty object as target object.

var result1 = [[{ name: "a", fruit: "apple" }, { name: "b", fruit: "banana" }], [{ name: "o", fruit: "orange" }], [{ name: "g", fruit: "grapes" }, { name: "s", fruit: "strawberries" }]],
    result2 = [{ country: "japan", color: "red" }, { country: "NewZealand", colour: "yellow" }, { country: "srilanka", colour: "green" }],
    result3 = result2.map((o, i) => Object.assign({}, o, { newproperty: result1[i] }));

console.log(result3);

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Apr 20, 2018 at 18:37

answered Apr 20, 2018 at 18:22

Nina Scholz

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2 Comments

MaxZoom Over a year ago

Not sure why you have included first parameter {} ?

Nina Scholz Over a year ago

@MaxZoom, without it updates result2, because that is how Object.assign works. if that is wanted, mapping is not required.

MaxZoom · Accepted Answer · 2018-04-20 19:43:08Z

1

As per documentation

The Object.assign( target, ...sources ) method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object.

var result1= [[{name:"a",fruit:"apple"},{name:"b",fruit:"banana"}],[{name:"o",fruit:"orange"}],[{name:"g",fruit:"grapes"},{name:"s",fruit:"strawberries"}]];

var result2 =[{country:"japan",color:"red"},{country:"NewZealand",colour:"yellow"},{country:"srilanka",colour:"green"}];

var result3 = result2.map((o, i) => Object.assign({newproperty: result1[i]}, o));

console.log(result3);

edited Apr 20, 2018 at 19:43

answered Apr 20, 2018 at 18:49

MaxZoom

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Comments

Antonio Pangallo · Accepted Answer · 2018-04-20 18:43:57Z

0

I would use something like:

var result1 = [
  [{name:"a",fruit:"apple"},{name:"b",fruit:"banana"}],
  [{name:"o",fruit:"orange"}],
  [{name:"g",fruit:"grapes"},{name:"s",fruit:"strawberries"}]
];
var result2 =[
  {country:"japan",color:"red"},
  {country:"NewZealand",colour:"yellow"},
  {country:"srilanka",colour:"green"}
];

var result3 = result2.map( (elm, index) => {
  var newproperty = result1[index].map(elm => { return { ...elm } } );
  return { ...elm, newproperty};
});

answered Apr 20, 2018 at 18:43

Antonio Pangallo

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