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javascriptinstanceoftypeof

What is the difference between typeof and instanceof and when should one be used vs. the other?

In my particular case:

callback instanceof Function

or 

typeof callback == "function"

does it even matter, what's the difference?

Additional Resource:

JavaScript-Garden typeof vs instanceof

Solution

  • Use instanceof for custom types:

    var ClassFirst = function () {};
var ClassSecond = function () {};
var instance = new ClassFirst();
typeof instance; // object
typeof instance == 'ClassFirst'; // false
instance instanceof Object; // true
instance instanceof ClassFirst; // true
instance instanceof ClassSecond; // false

    Use typeof for simple built in types:

    'example string' instanceof String; // false
typeof 'example string' == 'string'; // true

'example string' instanceof Object; // false
typeof 'example string' == 'object'; // false

true instanceof Boolean; // false
typeof true == 'boolean'; // true

99.99 instanceof Number; // false
typeof 99.99 == 'number'; // true

function() {} instanceof Function; // true
typeof function() {} == 'function'; // true

    Use instanceof for complex built in types:

    /regularexpression/ instanceof RegExp; // true
typeof /regularexpression/; // object

[] instanceof Array; // true
typeof []; //object

{} instanceof Object; // true
typeof {}; // object

    And the last one is a little bit tricky:

    typeof null; // object