JavaScript/ return an object in function

Question

I have an object with 3 fields: num which int, str which string and arr which array. So I define it:

function myClass(num, str, arr) {
   this.num = num;
   this.str = str;
   this.arr =arr;
}

Now I have function, which it return value is myClass. This function get string:

function myfunc(str){
   var str1 = str.split(" ");
   return myClass(1, str1[0], str1);
}

but when I run it, it returns undefine. How I return the myClass object?

Paul · Accepted Answer · 2013-05-10 17:49:15Z

5

You're missing the new keyword:

function myfunc(str){
   var str1 = str.split(" ");
   return new myClass(1, str1[0], str1);
}

answered May 10, 2013 at 17:49

Paul

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Comments

Alnitak · Accepted Answer · 2013-05-10 17:49:22Z

4

You need to return new myClass(...)

Without the new keyword, the myClass function just acts like a plain function that doesn't return anything (hence undefined).

With the new keyword, a new object will be created and passed as this, and that same object will be the default return value.

answered May 10, 2013 at 17:49

Alnitak

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Maizere Pathak.Nepal · Accepted Answer · 2013-05-10 17:52:31Z

-1

function myfunc(str){
   var str1 = str.split(" ");
   return new myClass(1, str1[0], str1);//add new keyword here
}

The new keyword will produce an object to which the keyword this will refer to.

answered May 10, 2013 at 17:52

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