<!DOCTYPE qhelp PUBLIC

"-//Semmle//qhelp//EN"

"qhelp.dtd">

<qhelp>

<overview>

<p>

Elements of array literal expressions that are omitted will be initialized to <code>undefined</code>.

However, such omitted elements are easy to miss and make code hard to read. They should be avoided.

</p>

</overview>

<recommendation>

<p>

Explicitly initialize the array elements to <code>undefined</code>. If you want to create an array

with a specific number of uninitialized elements, use the <code>Array</code> constructor instead.

</p>

</recommendation>

<example>

<p>

The following code snippet initializes <code>a</code> to an array of size ten by using omitted

elements.

</p>

<sample src="examples/EmptyArrayInit.js" />

<p>

This code is clearly hard to read, and should be replaced by the following snippet:

</p>

<sample src="examples/EmptyArrayInitGood.js" />

</example>

<references>

<li>D. Crockford, <i>JavaScript: The Good Parts</i>, Appendix C.6. O'Reilly, 2008.</li>

</references>

</qhelp>