Javascript : object properties aren't recognized

Question

I have a foo object as follow :

var foo =
{   
    "timer" : 
    {
        "hours" : 0, 
        "minutes" : 0, 
        "seconds" : 0,  
        "time" : new Date(1970, 0, 1, foo.timer.hours, foo.timer.minutes, foo.timer.seconds).getTime()                      
    }
};

The problem is that foo.timer.hours, foo.timer.minutes and foo.timer.seconds properties in new Date() aren't recognized because javascript console in chrome browser displays that :

Uncaught TypeError: Cannot read property 'timer' of undefined

So why foo.timer.hours, foo.timer.minutes and foo.timer.seconds properties in new Date() aren't recognized ?

Timer of undefined means, parent of timer, ie, foo is going undefined where ever you are trying to access it. — Rohith Murali
– Rohith Murali, Commented Jun 2, 2018 at 14:42

Ben West · Accepted Answer · 2018-06-02 14:47:13Z

2

foo isn’t defined until the end of the var foo = { ... }; statement. You could define these variables before defining foo.

var hours = 0, minutes = 0, seconds = 0;
var foo = {
    timer: {
        hours, minutes, seconds,
        time: new Date( 1970, 0, 1, hours, minutes, seconds ).getTime()
    }
};

answered Jun 2, 2018 at 14:47

Ben West

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3 Comments

totoaussi Over a year ago

Thank you, you're right, foo isn't defined until the end of the var foo = {...}

charlietfl Over a year ago

This is ugly. Doesn't allow storing the values in the object itself the way original intent seems to be

Ben West Over a year ago

Yeah I agree, the suggestions in other answers are better.

Ashish Ranjan · Accepted Answer · 2018-06-02 14:43:33Z

1

The way you are creating the foo object is incorrect... first create the object and use its properties, you are trying to refer the foo object in your time property when the variable foo hasn't been asigned yet..

var foo =
{   
    "timer" : 
    {
        "hours" : 0, 
        "minutes" : 0, 
        "seconds" : 0,  
                            
    }
};

foo["time"] = new Date(1970, 0, 1, foo.timer.hours, foo.timer.minutes, foo.timer.seconds).getTime();

console.log(foo)

answered Jun 2, 2018 at 14:43

Ashish Ranjan

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Comments

hashbytes · Accepted Answer · 2018-06-02 14:44:14Z

1

foo.time = new Date(1970, 0, 1, foo.timer.hours, foo.timer.minutes, foo.timer.seconds).getTime()

you can do this.

answered Jun 2, 2018 at 14:44

hashbytes

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Comments

Gerardo BLANCO · Accepted Answer · 2018-06-02 14:45:45Z

1

You are trying assign some values before those are initialize. You should split the declaration of the values and then you can add the time key/value function.

Hope this helps :>

var foo =
{   
    "timer" : 
    {
        "hours" : 0, 
        "minutes" : 0, 
        "seconds" : 0                   
    }
};

foo.timer['time'] = new Date(1970, 0, 1, foo.timer.hours, foo.timer.minutes, foo.timer.seconds).getTime();   
console.log(foo)

answered Jun 2, 2018 at 14:45

Gerardo BLANCO

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Comments

charlietfl · Accepted Answer · 2018-06-02 14:55:16Z

1

An alternate approach is add a getter to the object

var foo =
{   
    "timer" : 
    {
        "hours" : 0, 
        "minutes" : 0, 
        "seconds" : 0, 
        get time(){
           return new Date(1970, 0, 1, this.hours, this.minutes, this.seconds).getTime()
        }                       
    }
};

console.log(foo.timer.time)

answered Jun 2, 2018 at 14:55

charlietfl

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