Web Programming Step by Step, 2nd Edition

Lecture XX: Client-Side Validation

Reading: 15.3

Except where otherwise noted, the contents of this document are Copyright 2012 Marty Stepp, Jessica Miller, and Victoria Kirst. All rights reserved. Any redistribution, reproduction, transmission, or storage of part or all of the contents in any form is prohibited without the author's expressed written permission.

Regular expressions in JavaScript

• string.match(regex)
  • if string fits the pattern, returns the matching text; else returns null
  • can be used as a Boolean truthy/falsey test:
    var name = $("name").value;
if (name.match(/[a-z]+/)) { ... }
• an i can be placed after the regex for a case-insensitive match
  • name.match(/Marty/i) will match "marty", "MaRtY", ...

Replacing text with regular expressions

• string.replace(regex, "text")
  • replaces the first occurrence of given pattern with the given text
  • var str = "Marty Stepp";
str.replace(/[a-z]/, "x") returns "Mxrty Stepp"
  • returns the modified string as its result; must be stored
    str = str.replace(/[a-z]/, "x")
• a g can be placed after the regex for a global match (replace all occurrences)
  • str.replace(/[a-z]/g, "x") returns "Mxxxx Sxxxx"
• replace with empty string to use a regex as a filter
  • str = str.replace(/[^A-Z]+/g, "") turns str into "MS"