javascript - typeof和instanceof之间的区别是什么？何时应该使用另一个？(What is the difference between typeof and instanceof and when should one be used vs. the other?)

Question

In my particular case:

(在我的特殊情况下：)

callback instanceof Function

or

(要么)

typeof callback == "function"

does it even matter, what's the difference?

(甚至重要，有什么区别？)

Additional Resource:

(额外资源：)

JavaScript-Garden typeof vs instanceof

(JavaScript-Garden typeof vs instanceof)

  ask by farinspace translate from so

Answer 1

Use instanceof for custom types:(将instanceof用于自定义类型：)

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:(对于简单的内置类型，请使用typeof ：)

'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:(将instanceof用于复杂的内置类型：)

/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:

(而最后一个有点棘手：)

typeof null; // object