return a string in javascript

Question

i want to check if a number is even by use of function and return in Javascript. here goes my code. It should return true when number is even otherwise it should return false.

var isEven = function(number) {
    if(number%2 === 0) {
        return "true";
    } else {
        return "false";
    }
};

the code doesn't work. Instead it works when the quotation marks ( "...") around true and false are removed. Why? I mean the words true and false are strings, hence should be included inside quotation marks. please help,

The simplest way is just function isEven (num) { return num % 2 === 0 }. — gcampbell
– gcampbell, Commented Jun 25, 2016 at 10:56

Sebastian Simon · Accepted Answer · 2016-06-25 11:09:03Z

4

If you put true and false in quotation marks, it will return a string value, because "true" is a string, whereas true is not. If you want to return a boolean, just return true or false.

if(number % 2 === 0) return true;
else return false;

edited Jun 25, 2016 at 11:09

Sebastian Simon

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answered Jun 25, 2016 at 10:56

ozata

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Comments

Marek Woźniak · Accepted Answer · 2016-06-25 13:00:01Z

4

it should works:

var isEven = function(number) {
    return !Boolean(number % 2);
};

in additional how to create isOdd:

var isOdd = function(number) {
    return !isEven(number);
};

Reason why you can't return "true" for boolean:

Everything that exists between marks "..." in javascript's recognized as type string. This also applies to empty string "", some examples:

typeof("") => "string"
typeof("true") => "string"
typeof(true) => "boolean"

Comparison with others languages you have to pay attention for size of characters, fe:

typeof(TRUE) => "undefined" (because it could be name of variable)

In additional: be consider to use == and ===. Example:

"" == 0 => it's a true
"" === 0 => it's a false

Some examples for build-in Boolean function:

Boolean("") => false
Boolean("1") => true
Boolean("0") => true

edited Jun 25, 2016 at 13:00

answered Jun 25, 2016 at 10:56

Marek Woźniak

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1 Comment

Sebastian Simon Over a year ago

The use of Boolean is not necessary here. Just use return !(number % 2);.

Redu · Accepted Answer · 2016-06-25 11:31:20Z

0

You may try doing like this

var isEven = n => !(n%2);
console.log(isEven(1));
console.log(isEven(2));

answered Jun 25, 2016 at 11:31

Redu

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Comments

charlietfl · Accepted Answer · 2016-06-25 11:32:27Z

0

You don't need the if at all. Just return the result of the comparison

var isEven = function(number) {
   return number%2 === 0;
};

answered Jun 25, 2016 at 11:32

charlietfl

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