Hi I am very new to JS.
return this.foo("abc",function(){ //do something }); Can someone tell me what does the above line do?
- 1If you're new, what tutorial or book are you learning from?Greg Hewgill– Greg Hewgill2011-06-04 07:03:31 +00:00Commented Jun 4, 2011 at 7:03
- Which part do you need explained?dumbass– dumbass2024-10-09 08:35:20 +00:00Commented Oct 9, 2024 at 8:35
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5 Answers
- It grabs a reference to
this, which might be the DOM Window, a DOM element, or any other JavaScript object depending on how and where the above code is being run. - It (skipping ahead) prepares a new anonymous
Functionthat//does something. - It attempts to invoke a method
fooon objectthis, passing in two parameters"abc"and said anonymousFunction.
Very often when you see code that passes along an anonymous function (e.g. function(){ ... }), it is in fact holding on to that function in order to execute it not right away but at some later point in time, such as in response to a click event or a timer.
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looks like this.foo() is a function that returns something. so the return value is, what this.foo() returns.
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calls an instance method that gets as parameters a string and a function.
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It will return (yeah, like it is in English) the returned result of a function this.foo(...) (in the most simple form, ithe function this.foo(...) return "something" then the code will return "something"). The function this.foo("abc", function(){...}); is itself a function which receives 2 arguments: A string "abc" and a function(). The function this.foo will do something and return "something" to return by the main function. [x]
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It calls the function referenced by this.foo and passes two parameters: The string "abc" and an anonymous function function(){ //do something}. It then returns the result.
It is equivalent to:
var a = "abc"; var b = function(){ //do something }; return this.foo(a, b); Functions are first class objects in JS so you can pass them around like any other value.
I recommend to have a look at the MDC JavaScript guide.
