javascript how to return a number from an object variable

Question

So, I have a large object called con in that object, I have many variables, numbered sort of like an excel sheet, b19, b20, b21, etc.

I am trying to return a value from each one, but when I do a console log, It logs the entire function, not just the return.

Here's how the object is set up:

var con = {
    b13: function(){
        return 12600.535*Math.sqrt((con.b14+459.4)/459.4)
    },
    b14: function(){
        return 20;
    }
}

$(document).ready(function(){
    console.log(con.b13);
});

This outputs this into the console:

function(){
    return 12600.535*Math.sqrt((con.b14+459.4)/459.4)
}

So how do I format this so that it outputs the actual number in the equation?

console.log(con.b13()); Similarly, you will have to call the function b14 within b13 as con.b14() — Rajkumar Madhuram
– Rajkumar Madhuram, Commented Aug 20, 2014 at 20:58
The defineProperty syntax is quite verbose, but you can actually declare getters/setters through the object literal syntax. Check my answer... — plalx
– plalx, Commented Aug 20, 2014 at 21:17

cdhowie · Accepted Answer · 2014-08-20 20:59:21Z

2

You need to make b13 and b14 properties with a getter function:

var con = {};

Object.defineProperty(con, "b13", {
    get: function() {
        return 12600.535*Math.sqrt((con.b14+459.4)/459.4);
    }
});

Object.defineProperty(con, "b14", {
    get: function() { return 20; }
});

This will cause con.b13 and con.b14 to call the given functions, returning whatever the functions return.

answered Aug 20, 2014 at 20:59

cdhowie

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2 Comments

ntgCleaner Over a year ago

This is probably the proper and best way to do it, though the simple fix to just give a () at the end of the variable name works perfectly.

cdhowie Over a year ago

@ntgCleaner You use properties when the function represents data, and regular functions when the function represents an action. In this case they represent data, so property syntax should be preferred.

Gary Storey · Accepted Answer · 2014-08-20 20:59:47Z

2

Try console.log(con.b13()); . You are logging the function definition not executing it.

answered Aug 20, 2014 at 20:59

Gary Storey

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Comments

kirinthos · Accepted Answer · 2014-08-20 20:59:17Z

1

you don't define the properties as functions...

var con = {
  b13: 239487,
  b12: 923748
};

edit: if some properties need to be functions you have to call them e.g. con.b14(), not con.b14 as a property

answered Aug 20, 2014 at 20:59

kirinthos

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Comments

plalx · Accepted Answer · 2014-08-20 21:14:34Z

0

You can simply use es5 getters/setters.

var con = {
    get b13() {
        return 12600.535*Math.sqrt((con.b14+459.4)/459.4);
    },
    get b14() {
        return 20;
    }
};

answered Aug 20, 2014 at 21:14

plalx

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Comments

score 0 · Accepted Answer · 2014-08-21 03:28:16Z

0

The problem is that your object's properties are functions, but you are trying to call them as if they were values.

For example, if you wanted correctly log con.b13's value to the console, you would need to change the command to:

console.log(con.b13());

What this does is get what con.b13 returns rather than what it is.

If you don't want to go through the hassle of adding a () next to every reference, you can modify the object and define getters like this:

var con = {
    get b13() {
        return 12600.535 * Math.sqrt((con.b14 + 459.4) / 459.4)
    },

    get b14() {
        return 20;
    }
}

If you define the object like this, your original command console.log(con.b13) will work as intended.

edited Aug 21, 2014 at 3:28

answered Aug 20, 2014 at 21:32

user3886234

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