Any difference between explicit and implicit return in javascript function? - Stack Overflow

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Is there any difference when I explicitly return from a function vs. implicitly return?

Here's the code that puzzles me ATM:

function ReturnConstructor(arg){
    // Private variable. 
    var privateVar = "can't touch this, return ctor.";

    // This is what is being exposed to the outside as the return object
    return {
        print: function() {
            console.log("ReturnConstructor: arg was: %s", arg);
        }
    };
}

function NormalConstructor(arg){
    // Private variable. 
    var privateVar = "can't touch this, normal ctor";

    // This is what is being exposed to the outside as "public"
    this.print = function() {
            console.log("NormalConstructor: arg was: %s", arg);
        };
}

var ret = new ReturnConstructor("calling return");
var nor = new NormalConstructor("calling normal");

Both objects ('ret' & 'nor') seem the same to me, and I'm wondering if it's only personal preference of whomever wrote whichever article I've read so far, or if there's any hidden traps there.

Is there any difference when I explicitly return from a function vs. implicitly return?

Here's the code that puzzles me ATM:

function ReturnConstructor(arg){
    // Private variable. 
    var privateVar = "can't touch this, return ctor.";

    // This is what is being exposed to the outside as the return object
    return {
        print: function() {
            console.log("ReturnConstructor: arg was: %s", arg);
        }
    };
}

function NormalConstructor(arg){
    // Private variable. 
    var privateVar = "can't touch this, normal ctor";

    // This is what is being exposed to the outside as "public"
    this.print = function() {
            console.log("NormalConstructor: arg was: %s", arg);
        };
}

var ret = new ReturnConstructor("calling return");
var nor = new NormalConstructor("calling normal");

Both objects ('ret' & 'nor') seem the same to me, and I'm wondering if it's only personal preference of whomever wrote whichever article I've read so far, or if there's any hidden traps there.

• javascript
• function
• return

Share Follow asked Jan 9, 2014 at 23:43 NoctisNoctis 11.8k33 gold badges4545 silver badges8484 bronze badges

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2 Answers 2

Sorted by: Reset to default 6

When you use new, there's an implicit value. When you don't use new, there isn't.

When a function called with new returns an object, then that's the value of the new expression. When it returns something else, that return value is ignored and the object implicitly constructed is the value of the expression.

So, yes, there can be a difference.

Implicit return only happens for single statement arrow functions, except When arrow function is declared with {}, even if it’s a single statement, implicit return does not happen: link

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