What is array literal notation in javascript and when should you use it?
JavascriptArraysJslintLiteralsJavascript Problem Overview
JSLint is giving me this error:
>Problem at line 11 character 33: Use the array literal notation [].
var myArray = new Array();
What is array literal notation and why does it want me to use it instead?
It shows http://www.w3schools.com/JS/js_obj_array.asp">here</a> that new Array();
should work fine... is there something I'm missing?
Javascript Solutions
Solution 1 - Javascript
array literal notation is where you define a new array using just empty brackets. In your example:
var myArray = [];
It is the "new" way of defining arrays, and I suppose it is shorter/cleaner.
The examples below explain the difference between them:
var a = [], // these are the same
b = new Array(), // a and b are arrays with length 0
c = ['foo', 'bar'], // these are the same
d = new Array('foo', 'bar'), // c and d are arrays with 2 strings
// these are different:
e = [3], // e.length == 1, e[0] == 3
f = new Array(3); // f.length == 3, f[0] == undefined
>Reference: https://stackoverflow.com/a/931875/177125">What’s the difference between “Array()” and “[]” while declaring a JavaScript array?
Solution 2 - Javascript
See also: What’s wrong with var x = new Array();
Aside from the Crockford argument, I believe it is also due to the fact that other languages have similar data structures that happen to use the same syntax; for example, Python has lists and dictionaries; see the following examples:
// this is a Python list
a = [66.25, 333, 333, 1, 1234.5]
// this is a Python dictionary
tel = {'jack': 4098, 'sape': 4139}
Isn't it neat how Python is also grammatically correct Javascript? (yes, the ending semi-colons are missing, but those aren't required for Javascript, either)
Thus, by reusing common paradigms in programming, we save everyone from having to relearn something that shouldn't have to.
Solution 3 - Javascript
Aside from the Crockford argument, jsPerf says that it's faster. http://jsperf.com/new-vs-literal-array-declaration
Solution 4 - Javascript
After looking at @ecMode jsperf, I did some further tests.
When using push to add to the array new Array() is considerably faster on Chrome:
http://jsperf.com/new-vs-literal-array-declaration/2
Using index to add is slightly faster for [].