Javascript playing with object items

Question

I'm having 2 sets of object, an example:

var objA = {};
 objA.data1a = 100;
 objA.data2a = 70;
 objA.data3a = 16;
 objA.data4a = 37;
 objA.data5a = 88;
 //my ObjA will contain the following
 //{"data1a":100, "data2a":70, ......... "data5a":88}
var objB = {}
 objA.data1b = 19;
 objA.data2b = 5;
 objA.data3b = 7;
 objA.data4b = 6;
 objA.data5b = 2;
var getDifferences = {};
//I want to get the differences using a loop but I'm not sure how am I able to do so.
//I am able to do this currently
// getDifferences.data1 = objA.data1a - objB.data1b;
// getDifferences.data2 = objA.data2a - objB.data2b;
// getDifferences.data3 = objA.data3a - objB.data3b;

may I know if there's a loop to loop through an object so that for each loop I can minus and store the differences into another object?

• Nina Scholz: you may consider a better iterable structure like an array and not an object

Answer 1

An iteration over the keys. I assume, that objB should contain the other values.

var objA = { data1a: 100, data2a: 70, data3a: 16, data4a: 37, data5a: 88 },
 objB = { data1b: 19, data2b: 5, data3b: 7, data4b: 6, data5b: 2 },
 getDifferences = {};
Object.keys(objA).forEach(function (k) {
 var kk = k.substring(0, k.length - 1);
 getDifferences[kk] = objA[kk + 'a'] - objB[kk + 'b'];
});
document.write('<pre>' + JSON.stringify(getDifferences, 0, 4) + '</pre>');

More Example

What if.. my naming were different? EXAMPLE: var storeA = {}; {"1000": 532, "2020": 123} and var storeB = {}; {"1000": 200, "2020": 12}

var storeA = {"1000": 532, "2020": 123},
 storeB = {"1000": 200, "2020": 12},
 getDifferences = {};
Object.keys(storeA).forEach(function (k) {
 getDifferences[k] = storeA[k] - storeB[k];
});
document.write('<pre>' + JSON.stringify(getDifferences, 0, 4) + '</pre>');

Even more Example

in storeX obj and storeY obj. { '4100': 3060431, '4130': 4413045, '16386': 4191921, '17476': 4161761 } { '4100': 3332286, '4130': 7640173, '16386': 5773080, '17476': 4692493 }

var storeA = { '4100': 3060431, '4130': 4413045, '16386': 4191921, '17476': 4161761 },
 storeB = { '4100': 3332286, '4130': 7640173, '16386': 5773080, '17476': 4692493 },
 getDifferences = {};
Object.keys(storeA).forEach(function (k) {
 getDifferences[k] = Math.abs(storeA[k] - storeB[k]);
});
document.write('<pre>' + JSON.stringify(getDifferences, 0, 4) + '</pre>');

• shin1234: Thanks. What if.. my naming were different? EXAMPLE: var storeA = {}; {"1000": 532, "2020": 123} and var storeB = {}; {"1000": 200, "2020": 12}
• Nina Scholz: then you could map it directly.
• shin1234: I think it will be easier if I just list down the exact data I have.
• shin1234: I have this 2 set of data which i'm trying to get it to dynamically stores the differences.
• shin1234: in storeX obj and storeY obj. { '4100': 3060431, '4130': 4413045, '16386': 4191921, '17476': 4161761 } { '4100': 3332286, '4130': 7640173, '16386': 5773080, '17476': 4692493 }

Answer 2

Yes, you actually can do this using Object.keys() function. Here is my example to do this:

var objA = {};
 objA.data1a = 100;
 objA.data2a = 70;
 objA.data3a = 16;
 objA.data4a = 37;
 objA.data5a = 88;
 //my ObjA will contain the following
 //{"data1a":100, "data2a":70, ......... "data5a":88}
var objB = {}
 objB.data1b = 19;
 objB.data2b = 5;
 objB.data3b = 7;
 objB.data4b = 6;
 objB.data5b = 2;
var getDifferences = {};
/// =================
var keysA = Object.keys(objA);
var keysB = Object.keys(objB);
if (keysA.length == keysB.length) {
 for (i = 0; i < keysA.length; i++) {
 getDifferences['data'+i] = objA[keysA[i]] - objB[keysB[i]];
 }
}
console.log(getDifferences);