There’s no difference. Both are valid ways to get the JavaScript parser to treat your function as an expression instead of a declaration. Note that + and ! will also work, and are sometimes used by minifiers to save a character of size: +function() { var foo = ‘bar’; }(); !function() { var foo = … Read more
From Douglass Crockford’s style convention guide: (search for “invoked immediately”) When a function is to be invoked immediately, the entire invocation expression should be wrapped in parens so that it is clear that the value being produced is the result of the function and not the function itself. So, basically, he feels it makes more … Read more
Douglas Crockford has a new idiomatic way of achieving the above – his old technique was to use an inner function to bind the variables, but the new technique uses a function maker. See slide 74 in the slides to his “Function the Ultimate” talk. [This slideshare no longer exists] For the lazy, here is … Read more
Array(5) gives you an array with length 5 but no values, hence you can’t iterate over it. Array.apply(null, Array(5)).map(function () {}) gives you an array with length 5 and undefined as values, now it can be iterated over. Array.apply(null, Array(5)).map(function (x, i) { return i; }) gives you an array with length 5 and values … Read more
There is no difference for a simple object without methods as in your example. However, there is a big difference when you start adding methods to your object. Literal way: function Obj( prop ) { return { p : prop, sayHello : function(){ alert(this.p); }, }; } Prototype way: function Obj( prop ) { this.p … Read more
My view is to always use ++ and — by themselves on a single line, as in: i++; array[i] = foo; instead of array[++i] = foo; Anything beyond that can be confusing to some programmers and is just not worth it in my view. For loops are an exception, as the use of the increment … Read more
Update for ES6 modules Inside native ECMAScript modules (with import and export statements) and ES6 classes, strict mode is always enabled and cannot be disabled. Original answer This article about Javascript Strict Mode might interest you: John Resig – ECMAScript 5 Strict Mode, JSON, and More To quote some interesting parts: Strict Mode is a … Read more