Add an existing var to a new object in JavaScript and loop through them

Question

I find numerous guides on how to add variables to existing objects, but nowhere how to add an "existing" variable to an existing object.

I have a whole list with variables already defined in my script. e.g.: a, b, c, d. and they all have their own values. Now I want to call a function on all these variables and then show the variable-names and outcome in console. Therefor I want to create an object out of them to loop through. How do I do this?

This is my workflow: Values are created in various places in the script:

a = 1.333;
b = 1.64252345;
c = 2.980988;

I create the object and try to add the already existing variables (this is where I fail):

var abc = {};
abc.a;
abc.b;
abc.c;

I want to loop through the object, flooring all numbers, and printing the variable-name with the returned number:

var i;
for (i = 0; i < abc.length; ++i) {
    var variablename = Object.keys(abc[i]);
    var flooredvalue = floor(abc[i]);
    var abc[i] = flooredvalue; // Save the floored value back to the variable.
    console.log(variablename+": "+flooredvalue);
}

My desired output in console.log:

a = 1
b = 1
c = 2

There seems to be a lot of misunderstanding here. Objects have properties, the names of properties are not connected to any variables names. Then, floor is a method of Math object, not window. Also, objects don't have length property, you need for..in loop to iterate objects. — Teemu
– Teemu, Commented Feb 6, 2016 at 8:20
How can I loop through a list of variables, floor them all, and print the variablename + flooredvalue in the console? — mesqueeb
– mesqueeb, Commented Feb 6, 2016 at 8:22
How can I loop through a list of variables.. You can't do it with loop unless you place them into object (i.e. make them object properties). — hindmost
– hindmost, Commented Feb 6, 2016 at 8:22
@hindmost How can I do it without a loop but very easily to a list of variables? Because I need to do this to around 30 variables... — mesqueeb
– mesqueeb, Commented Feb 6, 2016 at 8:24

rrk · Accepted Answer · 2016-02-06 08:40:02Z

2

Looping through the array of object keys will be a good idea.

a = 1.333;
b = 1.64252345;
c = 2.980988;

var abc = {};
abc.a = a;
abc.b = b;
abc.c = c;

var i;
var keys = Object.keys(abc);
console.log(abc['a'])
for (i = 0; i < keys.length; i++) {
    var key = keys[i];
    var flooredvalue = Math.floor( abc[key] );
    abc[key] = flooredvalue;
    window[key] = flooredvalue; //global variable change.
}
console.log(a);
console.log(b);
console.log(c);

edited Feb 6, 2016 at 8:40

answered Feb 6, 2016 at 8:25

rrk

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4 Comments

Ananthaprakash Over a year ago

when iterating over object, we can use for...in for(key in abc){ console.log(Math.floor(abc[key])); }

mesqueeb Over a year ago

Thank you very much. This worked, but only inside the for-loop function. Once I tried console.log(a) outside the loop at the bottom, I get the original value. Can I have the floored value saved to the original variable inside the for-loop?

rrk Over a year ago

@Ananthaprakash yes. It is the easiest way, but the thing is that, its supported for IE10+ only. So, I tried to make a more general solution. This supports IE9+

rrk Over a year ago

@mesqueeb If you want to change the original variables, then you'll need to do window.a I'll update the answer.

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