Functions That Return Values Can Be Used in Expressions : Function « Language Basics « JavaScript DHTML

Functions That Return Values Can Be Used in Expressions


JavaScript Unleashed, Third Edition
by Richard Wagner and R. Allen Wyke 

ISBN: 067231763X
Publisher Sams CopyRight 2000


  <title>JavaScript Unleashed</title>
  <script type="text/javascript">
    function isPhone(aString) {
      var aChar = null;
      var status = true;
      if(aString.length != 13) {
        status = false;
        for(var i = 0; i <= 12; i++) {
          aChar = aString.charAt(i);
          if ( i == 0 && aChar == "(" ){
            if( i == 4 && aChar == ")" ){
              if( i == 8 && aChar == "-" ){
                if( parseInt(aChar,10) >= 0 && parseInt(aChar,10) <= 9 ){
                }else {
                  status = false;
  // -->
  <script type="text/javascript">
    var userInput = "(800)555-1212";    
    if(isPhone(userInput)) {
      document.writeln("Thank you for your phone number.");
      document.writeln("I will have a representative get you");
      document.writeln("more information.");
      document.writeln("Please re-enter your phone number");
      document.writeln("using the format (###)###-####");


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