how to create variables from key value object pair in javascript

Question

I have an object like this:

Object {geom: "-116.2, 35.6", hazard_c_5: "0.970118393901, 0.904556039223", hazard_c_6: "0.970118393901, 0.904556039223", iml: "0.005, 0.007", pga_mean: "0.987965748334, 0.958177134411"

How can I create a variable for each key and set its value to the keys respective value?

I was trying this:

for(i in data) {
    console.log(i, data[i]);
}

But it's not clear to me how to set i to a variable and data.[i] to the variables value?

I am after:

var geom = "-116.2, 35.6";
var hazard_c_5 = "0.970118393901, 0.904556039223";
...

EDIT

I should also mention that the number of key value pairs in data will change

Answer 1

There is the with statement, which does exactly that.

var data = {
    geom: "-116.2, 35.6",
    hazard_c_5: "0.970118393901, 0.904556039223",
    hazard_c_6: "0.970118393901, 0.904556039223",
    iml: "0.005, 0.007",
    pga_mean: "0.987965748334, 0.958177134411"
}

with(data) {
    console.log(geom, iml);
}

Please note, using with stops the JS Engine from making use of several optimizations and there is usually a better way of doing things than that.

Answer 2

As long as you want to make global variables, you can just create them as properties in the window object:

for(i in data) {
  window[i] = data[i];
}

Now you can use them just as you would use global variables. The only practical difference between window properties and global variables is that window properties can be deleted.

Answer 3

Try this:

(function (context) {
    var data = {
        geom: "-116.2, 35.6",
        hazard_c_5: "0.970118393901, 0.904556039223",
        hazard_c_6: "0.970118393901, 0.904556039223",
        iml: "0.005, 0.007",
        pga_mean: "0.987965748334, 0.958177134411"
    };
    for(var i in data) {
         context[i] = data[i];
    };
    alert(geom);
})(this)

Answer 4

The following will do what you asked for, but why don't you use the object itself? :/

var myObject = {
    x: 1,
    y: 2,
    z: 3
};

for( i in myObject ) {
    this[i] = myObject[i];
    console.log( this[i] );
}

Answer 5

Why would you EVER do this?

This is simply wrong.

Of course you can (but shouldn't) use eval like `eval("var geom = -116.2, 35.6;") but trust me, you don't need this.

I hope you know that you can access the geom value by using obj.geom .

But you ask me: Why I shouldn't?

• Performance : This will slow down your app. This will show you how much improvements Hugo Bonacci got by simply getting rid of these evals.

• Security : An experienced developer could potentially inject code into your application. This can be harmful in several ways.

• Readabilty and debugging : Where are these variables coming from? Why creating them using strings? And, what this eval function does?

That's it. But you can (shouldn't) use eval. But don't use eval.

Answer 6

edit: before negative voting this answer please RTFA , I suggest to NOT use evil.

You can do evil eval:

for (var i in obj) {
    eval("var " + i + " = " + obj[i] + ";");
}

but it's a bad bad bad practice, so you should avoid as much as possible. Instead use the property of the object:

var geom = obj.geom;

but if the problem is that you don't know the properties of an object then you can access them using square brackets:

var foo = obj["geom"];

where "geom" is a string with the name of the property, ie:

var key = "geom"
//later in the code
var foo = obj[key]