JS - add multiple dict values into a dict key

Question

I have a dictionary as as shown below. I am trying to add dict values into them. This is what it stars with

var animals = {
        flying : {},
        underground : {},
        aquatic : {},
        desert : {}
    };

For example: If I wanted to add d = {dove : [<some list>] } into animal[flying], how would i do it? I cannot enter the values manually as thus i am running a loop, I am able to write it manually, but not with program.

I have tried animals[flying] = d, this would work for the first time, but when i try to add another value it would be replaced and not appended.

In the end I am looking for something like this: This is what it ends with

var animals = {
        flying : {
            dove : [<list>],
            sparrow : [<list>],

        },
        underground : {
            rabbits : [<list>],
            squirrel : [Squirrel],

        },
        aquatic : {
            dolphin : [<list>],
            whale : [Squirrel],

        },
        desert : {
            camel : [<list>],
            antelope : [<list>],

        },
    };

yuvi · Accepted Answer · 2017-11-01 21:13:01Z

1

well because

myDict[subcat] = x

assigns it. You're working with lists. Think about it - when have you ever added an item to a list this way? Of course that overwrites your previous entry. What you want instead is to push the variable into the array (also, this isn't python. Lists are called Arrays and Dictionaries are called Objects. There is a distinction, but that's beyond the scope of an answer here. Google it).

So do this:

myDict = {
    subCat: [],
}

And then when you loop:

myDict[subCat].push(x)

answered Nov 1, 2017 at 21:13

yuvi

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dave · Accepted Answer · 2017-11-01 21:17:11Z

1

I think what you want to do is:

animals["flying"] = Object.assign(animals["flying"], d);

E.g.

animals = {
    flying: {}
}

d = { dove: [1, 2, 3] }
Object.assign(animals["flying"], d);
d = { sparrow: [1, 2, 3] }
Object.assign(animals["flying"], d);
console.log(animals); //{"flying":{"dove":[1,2,3],"sparrow":[1,2,3]}}

edited Nov 1, 2017 at 21:17

answered Nov 1, 2017 at 21:12

dave

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1 Comment

Sebastian Simon Over a year ago

That’s equivalent to Object.assign(animals["flying"], d);. Object.assign already mutates the first argument. Also animals["flying"] can be rewritten as animals.flying.

matt · Accepted Answer · 2017-11-01 21:16:51Z

0

var newAnimal = {name: 'bird'};    
if(animals['flying']['dove'] && animals['flying']['dove'].length > 0) {
   //List already exists so add the new animal
   //TODO also check if the animal is already in the list?
   animals['flying']['dove'].push(newAnimal);
}else {
   //Create the new list
   animals['flying']['dove'] = [newAnimal];
}

edited Nov 1, 2017 at 21:16

answered Nov 1, 2017 at 21:11

matt

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