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   ► KBWebsite Scri...JavaScript a...Beginners Co...   Print This     
  From the August 2015 Issue of Prestwood eMag
 
JavaScript Beginners Corner:
JavaScript Literals (quote or apostrophe)
 
Posted 16 years ago on 11/4/2008 and updated 1/18/2009
JavaScript Code Snippet:
 A flashcard from our JavaScript Flashcards Library
 A code snippet from our JavaScript Code Snippets Page

KB101522

General Info: Programming Literals

A value directly written into the source code of a computer program (as opposed to an identifier like a variable or constant). Literals cannot be changed. Common types of literals include string literals, floating point literals, integer literals, and hexidemal literals. Literal strings are usually either quoted (") or use an apostrophe (') which is often referred to as a single quote. Sometimes quotes are inaccurately referred to as double quotes.

Languages Focus: Literals

In addition to understanding whether to use a quote or apostrophe for string literals, you also want to know how to specify and work with other types of literals including floating point literals. Some compilers allow leading and trailing decimals (.1 + .1), while some require a leading or trailing 0 as in (0.1 + 0.1). Also, because floating point literals are difficult for compilers to represent accurately, you need to understand how the compiler handles them and how to use rounding and trimming commands correctly for the nature of the project your are coding.

JavaScript Literals

String literals use either an apostrophe (also known as a single quote) as in 'Prestwood' or quoted as in "Prestwood". If you need to embed an apostrophe in an apostrophe-literal or a quote in a quoted-literal, precede it with a slash as in \' and \".

Syntax Example:
Alert("Hello");
Alert("Hello \"Mike\".")
  
Alert('Hello');
Alert('Hello Mike\'s website.')
 
//Does JavaScript evaluate this simple
//floating point math correctly? No! 
if ((.1 + .1 + .1) == .3) {
 document.write("Correct")
} else {
 document.write("Not correct")
}

Working Example

<html>
<body>
 
<h1>JavaScript Literals</h1>
<script language=JavaScript>
<!--
//Preceding decimals.

if ((.1 + .1 + .1) == .3) {
 document.write("Correct")
} else {
 document.write("Not correct")
}
 
//Trailing decimals.
if ((1.0 + 1. + 1) == 3.0) {
 document.write("Correct")
} else {
 document.write("Not correct")
}
//-->
</script>
 
</body>
</html>

More Info

Definition:  Programming Literals

Comments

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Comment 1 of 1

Great website. Lots of information to Read. Great Man Keep Posting. Thanks.

---
John
Posted 8 years ago
 
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Code Contributed By Mike Prestwood:

Mike Prestwood is a drummer, an author, and creator of the PrestwoodBoards online community. He is the President & CEO of Prestwood IT Solutions. Prestwood IT provides Coding, Website, and Computer Tech services. Mike has authored 6 computer books and over 1,200 articles. As a drummer, he maintains play-drums.com and has authored 3 drum books. If you have a project you wish to discuss with Mike, you can send him a private message through his PrestwoodBoards home page or call him 9AM to 4PM PST at 916-726-5675 x205.

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