Array literals should always be preferred to Array constructors.

Array constructors are error-prone due to the way their arguments are interpreted. If more than one argument is used, the array length will be equal to the number of arguments. However, using a single argument will have one of three consequences:

• If the argument is a number and it is a natural number the length will be equal to the value of the argument.
• If the argument is a number, but not a natural number an exception will be thrown.
• Otherwise the array will have one element with the argument as its value.

For these reasons, if someone changes the code to pass 1 argument instead of 2 arguments, the array might not have the expected length. To avoid these kinds of weird cases, always use the more readable array.

Noncompliant Code Example

var a1 = new Array(x1, x2, x3);  // Noncompliant. Results in 3-element array.
var a2 = new Array(x1); // Noncompliant and variable in results
var a3 = new Array();  // Noncompliant. Results in 0-element array.

Compliant Solution

var a1 = [x1, x2, x3];
var a2 = [x1];
var a3 = [];