ECMA-262. Skilldrick » Closures explained with JavaScript. Last year I wrote A brief introduction to closures which was meant to help people understand exactly what a closure is and how it works.
I’m going to attempt that again, but from a different angle. I think with these kinds of concept, you just need to read as many alternative explanations as you can in order to get a well rounded view. First-class functions As I explained in Why JavaScript is AWESOME, one of the most powerful parts of JavaScript is its first-class functions. So, what does “first-class” mean in a programming language?
Can be stored in variables and data structures can be passed as a parameter to a subroutine can be returned as the result of a subroutine can be constructed at runtime has intrinsic identity (independent of any given name) So, functions in JavaScript are just like objects. The ability to nest functions gives us closures. Nested functions Here’s a little toy example of nested functions: The important thing to note here is that there is only one f defined.
Nobel prize winners demo. jQuery & JavaScript Articles For The Community. Adequately Good - JavaScript Scoping and Hoisting - by Ben Cherry. Do you know what value will be alerted if the following is executed as a JavaScript program?
Var foo = 1; function bar() { if (! Foo) { var foo = 10; } alert(foo); } bar(); If it surprises you that the answer is "10", then this one will probably really throw you for a loop: var a = 1; function b() { a = 10; return; function a() {} } b(); alert(a); Here, of course, the browser will alert "1". Scoping in JavaScript One of the sources of most confusion for JavaScript beginners is scoping. #include <stdio.h> int main() { int x = 1; printf("%d, ", x); // 1 if (1) { int x = 2; printf("%d, ", x); // 2 } printf("%d\n", x); // 1 } The output from this program will be 1, 2, 1 .
Var x = 1; console.log(x); // 1 if (true) { var x = 2; console.log(x); // 2 } console.log(x); // 2 In this case, Firebug will show 1, 2, 2 . To a lot of programmers who are used to languages like C, C++, C#, or Java, this is unexpected and unwelcome. Declarations, Names, and Hoisting These are of the form function foo() {} . Books/Javascript.pdf. Developer Network. Learning Advanced JavaScript. JavaScript Prototypal Inheritance - My 5 Cents From Web Reflection. © Andrea Giammarchi - 23 March 2008 Summary JavaScript is the world's most misunderstood programming language, and even if we use them from about 10 years, there is still confusion about the basis of its prototypal inheritance nature.
This page aim is to clarify this aspect of this wonderful scripting language that a lot of developers still do not perfectly understand. I hope this page will be useful even if I know my English is not good as my JavaScript knowledge is (so, sorry for language typos). top menu Object Quite everything, in JavaScript, inherits from Object. (Object instanceof Function) === (Function instanceof Object) Above example is true because Object is a constructor, and a constructor in JavaScript is always a Function. (Function.prototype instanceof Object) === (function(){} instanceof Object) These case describes the begin of prototypal hierarchy. Note 1: this assertion is an ambiguous exception, and it is probably the only one in the root of inheritance: Learning JavaScript Programming Language through Video Lectures.
I decided I wanted to learn JavaScript Programming language better.
I had been programming in it now and then but I had never really developed any good skills in it. If you have read about this blog page then you know that I also run Free Science Online blog which is all about free video lectures online. In my May's post I had found some really good programming video lectures, 13 of them being on JavaScript. Since I run this video lecture blog, I obviously have great interest in video lectures, so why not try to learn better JavaScript from these video lectures?
These lectures are given by Douglas Crockford who is a senior JavaScript Architect at Yahoo!. First four lectures are on the basics of language: Sometimes Yahoo! The next three lectures are on Advanced JavaScript: Then there are 6 more lectures on JavaScript which should probably be viewed only after you have viewed the ones just mentioned. QuirksMode - for all your browser quirks. Standard ECMA-262. Standard ECMA-262 ECMAScript® 2017 Language Specification 8th edition (June 2017) This Standard defines the ECMAScript 2017 general-purpose programming language.
The following files can be freely downloaded: Kindly note that the normative copy is the HTML version; the PDF version has been produced to generate a printable document. This 8th edition has been prepared under the Ecma RF patent policy. The latest drafts are available at: Reporters should generally only file bugs if the bug is still present in the latest drafts. Please find hereafter the place to file bugs: The previous replaced "historical" editions of this Ecma Standard are available here. Eloquent JavaScript.