How to create a function to check key values in array javascript

Question

I have a function that I'm trying to add a new array to the object. I keep getting an error 'target.push is not a function'.

Here is my function

    function targetChange(target, source) {
        Object.keys(source).forEach(function(keys) {
            for(i=0; i<source.length; i++) {
                target[keys].push(source[keys]);
            }                 
        });
        console.log(target);
    }

data:

source = {
    BasinId: 123,
    subBasinId: 45,
    SubBasinName: newSubBasin
}
target = {
    BasinId: (array of hundreds of ids),
    subBasinId: (array of hundreds of ids),
    SubBasinName: (array of hundreds of names)
}

I want to return source inside target.. I want to just add the new values to the existing object

I'm passing in an object as target that is set up like this {key: value, key: value, ...}. The source is set up the same way, but I can't seem to get it to add the new source to the target. Any ideas?? I've been stuck on this one for awhile now.

Object.keys(source).forEach(function(keys) { is already looping through the keys! — ibrahim mahrir
– ibrahim mahrir, Commented Apr 4, 2017 at 19:53
Can you do a console.log(target); at the beginning of your function? Are you sure, target[SAMPLE_KEY] is an array? (Or has the method push)? — Dave Chen
– Dave Chen, Commented Apr 4, 2017 at 19:54
here is the console.log for target: Object BasinId : Array[95] SubBasinId : Array[95] SubBasinName : Array[95] length : 95 — JBaldwin
– JBaldwin, Commented Apr 4, 2017 at 19:54

ibrahim mahrir · Accepted Answer · 2017-04-04 20:52:27Z

1

This should work:

function targetChange(target, source) {
  Object.keys(source).forEach(function(key) {
    var s = source[key], t = target[key]; // shorthands
    for(var i = 0; i < s.length; i++) {   // loop through s (source[key]) array
      t[t.length++] = s[i];               // add the current item to t (target[key]) array
    }
  });
  console.log(target);
}

var source = {
    BasinId: [123],
    subBasinId: [45],
    SubBasinName: ["newSubBasin"]
};
var target = {
    BasinId: [1, 2],
    subBasinId: [3, 4],
    SubBasinName: ["old1", "old2"]
};

targetChange(target, source);

edited Apr 4, 2017 at 20:52

answered Apr 4, 2017 at 20:06

ibrahim mahrir

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9 Comments

JBaldwin Over a year ago

I get the following error Uncaught TypeError: target[key].push is not a function

JBaldwin Over a year ago

I get that error when I try to save the new added values

ibrahim mahrir Over a year ago

@JBaldwin It's probable that target[key] doesn't exist yet! I added some fixes, check them!

ibrahim mahrir Over a year ago

@JBaldwin Well, first, you haven't explain what you really want. Second, you maybe posted the wrong example. Please post a full example with inputs and desired outputs and the logic behind what you're trying to implement! By the way what error?

JBaldwin Over a year ago

I said I wanted to ADD the source to the target. The error is the same one I posted in my first comment on this discussion.

|

Pedro Mosquera · Accepted Answer · 2017-04-04 19:58:52Z

1

You can't call a push method over a JSON

Change:

target[keys].push(source[keys]);

For:

target[keys] = source[keys];

You'll need to remove the for loop.

answered Apr 4, 2017 at 19:58

Pedro Mosquera

415 bronze badges

Comments

Nina Scholz · Accepted Answer · 2017-04-04 20:24:35Z

1

You need to check if the target property is falsy, then assign an array. Then push the value.

function targetChange(target, source) {
    Object.keys(source).forEach(function(key) {
        target[key] = target[key] || [];
        target[key].push(source[key]);
    });
}

var source = { BasinId: 123, subBasinId: 45, SubBasinName: 'newSubBasin' },
    target = { BasinId: [0, 1, 2, 3, 4], subBasinId: [10, 11, 12, 13, 14], SubBasinName: ['a', 'b', 'c', 'd', 'e'] };

targetChange(target, source);

console.log(target);

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

edited Apr 4, 2017 at 20:24

answered Apr 4, 2017 at 19:56

Nina Scholz

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8 Comments

kind user Over a year ago

And what does it change anyways?

JBaldwin Over a year ago

it's not changing anything it's adding another array to the object bc the user is adding a new subBasin

JBaldwin Over a year ago

that assigns the source to the target.. I want to just add the source to the existing data of target.. how can I do that

JBaldwin Over a year ago

I added data so you can see what I have and want

Nina Scholz Over a year ago

is the given source an array of objects?

|

JBaldwin · Accepted Answer · 2017-04-04 20:51:32Z

1

I was able to get it to work this way:

    function targetChange(target, source) {

        Object.keys(source).forEach(function(key) {
            for(i=0;i<source.length;i++) {
                target[key][target[key].length++] = source[key][i];
            }
        });

    }

answered Apr 4, 2017 at 20:51

JBaldwin

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1 Comment

ibrahim mahrir Over a year ago

My guess was right: target[key] is not an array, it's an array-like object thus not inheriting the methods of Array.prototype!

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