CODEWITHSUNDEEP
javascriptfunction
Hye Shusho
Hye Shusho

Reputation: 309

Why is it these two javascript functions seem to not be getting along...what am I doing wrong?

I'm pretty sure this is n00b question, but I'm completely new to javascript. I'm wondering why this code only prints "hello" but when I comment out the first function, that's when I get the second function to print the other two words. How does this make sense?

var function1 = createFunction();
function createFunction()
{
  console.log("hello");
}
function1(); 

function createFunctionPrinter(word)
{
  console.log(word);
}

var printSample = createFunctionPrinter('sample');
var printNoo = createFunctionPrinter('noo');

printSample(); //should console.log('sample');
printNoo(); //should console.log('noo');

Upvotes: 2

Views: 57

Answers (4)

ibrahim mahrir
ibrahim mahrir

Reputation: 31682

var function1 = createFunction();

function createFunction()
{
    // return a function that prints a message
    return function() {
        console.log("hello");
    }
}

function1();

Upvotes: 0

Angelos Chalaris
Angelos Chalaris

Reputation: 6747

Fixing function1 and createFunction() should be easy, provided the fact no arguments are needed for this. Simply set var function1 = createFunction without () and you it will effectively make function1 call createFunction as if that was the function's name.

createFunctionPrinter() is a bit different. My preferred approach is the use of a prototype, which will take an argument (word) when called, and then when you call its print() method, it will essentially print your text. The assignment of printSample and printNoo is similar, but you have to use the new keyword. Finally, to make the functions print, use something like printSample.print(). 

function createFunction() {
  console.log("hello");
}

function createFunctionPrinter(word) {
  this.word = word;
  this.print = function() {
    console.log(word);
  }
}

var function1 = createFunction;
function1();

var printSample = new createFunctionPrinter('sample');
var printNoo = new createFunctionPrinter('noo');

printSample.print();
printNoo.print();

P.S.: This might not the intended use of prototypes, but I believe it will make your life easier to use them in this case.

Upvotes: 1

ppasler
ppasler

Reputation: 3719

If you want to refer to an method, you should leave the (), as the function call return undefined.

See this example

function createFunction()
{
  console.log("hello");
}
var function1 = createFunction;
function1(); 

function createFunctionPrinter(word)
{
  console.log(word);
}

var printSample = createFunctionPrinter;
var printNoo = createFunctionPrinter;

printSample('sample'); //should console.log('sample');
printNoo('noo'); //should console.log('noo');

Upvotes: 1

Quentin
Quentin

Reputation: 943214

function1 is the return value of calling createFunction which is undefined because createFunction has no return statement.

undefined is not a function, so calling function1() raises an exception and execution halts.

Upvotes: 3

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