JavaScript Cookbook

Chapter 1. Working with JavaScript Strings

1.0. Introduction

JavaScript strings are the most important component of JavaScript, probably used more than any other data type. Though you may get numeric values from web page forms, the values are retrieved as strings, which you then have to convert into numeric values.

Strings are also used as parameters when invoking server-side application calls through Ajax, as well as forming the basic serialization format of every JavaScript object. One of the methods that all JavaScript objects share is toString, which returns a string containing the serialized format of the object.

A String Primitive

A JavaScript string can be both a primitive data type or an object. As a primitive type, it joins with four other JavaScript primitive types: number, Boolean (true or false), null (no value), and undefined (unknown). In addition, as a primitive data type, strings are also JavaScript literals: a collection that includes numbers (as either floating point or integer), the literal format for arrays, objects, and regular expressions, as well as numbers and Booleans.

Note

We’ll see more about the literal formats for the various JavaScript objects throughout the book.

A string is zero or more characters delimited by quotes, either single quotes:

'This is a string'

Or double quotes:

"This is a string"

There is no rule for which type of quote to use. If you’re including single quotes within the text, you’ll most likely want to use double quotes:

"This isn't a number." ...