skannar streng og finnur t‡kn!!!
 
  var myString = "Have a nice day!";
  var index = myString.indexOf("a");
  while (index != -1) {
    alert(index);
    index = myString.indexOf("a", index + 1); // start search after last match found
  }




<SCRIPT language="JavaScript">
<!-- Hide from older browsers

  var parsed = true;
  var validchars = "abcdefghijklmnopqrstuvwxyz0123456789@.-";
  var email = prompt("What is your email address?", "nobody@nowhere.com");
  
  for (var i=0; i < email.length; i++) {
    var letter = email.charAt(i).toLowerCase();
    if (validchars.indexOf(letter) != -1)
      continue;
    alert("Invalid character: " + letter);
    parsed = false;
    break;
  }
  
  if (parsed) alert("Your email address contains all valid characters.");

// Stop hiding -->
</SCRIPT>





// Copyright (C) 2001.  Gabriel Weinberg, yegg@alum.mit.edu

// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.

// You should have received a copy of the GNU Lesser General Public
// License along with this library (license.txt); if not, write to the
// Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
// MA 02111-1307 USA

// This source file is called oj.string.js and is part of the 
// Open JavaScript library available at javascript.malism.com


// This function deletes non-breaking spaces from a given string.
function deleteNbsp(str) {return replaceString('&nbsp;',' ',str);}


// This function replaces breaking spaces with non-breaking spaces
// for a given string.
function replaceNbsp(str) {return replaceString(' ','&nbsp;',str);}


// This function deletes the whitespace from a given string.
function deleteSpacing(str) {return replaceString(' ','',str);}


// This function turns a given string into a javaName, which is a
// string with no spaces where the first letter of the first word is
// lower case and the first letter of each subsequent word is upper case.
function javaName(str) {
  
  // First trim the string.
  str = trim(str);

  // Get an array of the words.
  var word = str.split(' ');

  // For each word.
  for (var i=0; i<word.length; i++) {

    // Make sure the first letter is upper case.
    word[i] = upper(word[i].substring(0,1)) + word[i].substring(1,word[i].length);

    // Trim the word.
    word[i] = trim(word[i]);
  }

  // Now make the first letter lower case.
  word[0] = lower(word[0].substring(0,1)) + word[0].substring(1,word[0].length);

  // Join the words.
  var javaName = word.join('');
  
  // Get rid of apostrophes.
  javaName = replaceString("'",'',javaName)

  // Return the string.
  return javaName;
}


// This function converts a given string to lower case.
function lower(str) {return str.toLowerCase();}


// Thie function replaces the given string oldS with the given string
// newS in the given string fullS.
function replaceString (oldS,newS,fullS) {
  // For each character in fullS.
  for (var i=0; i<fullS.length; i++) {      

    // If oldS is there.
    if (fullS.substring(i, i + oldS.length) == oldS) {

      // Replace oldS with newS.
      fullS = fullS.substring(0,i)+newS+fullS.substring(i+oldS.length,fullS.length);
    }   
  }   

  // Return the string.
  return fullS;
return true;}


// This function trims a given string of leading and trailing whitespace.
function trim(str) {

  // Make sure the given string is a string.
  str = str.toString();
  
  // Move through the string until you don't hit whitespace.
  var start = 0;
  while ((start < str.length) && ( (str.charAt(start) == ' ') || (str.charAt(start) == '\n')|| (str.charAt(start) == '\r') || (escape(str.charAt(start))=='%A0') || ( str.charAt(start) == escape('&nbsp;') ) ) ) ++start;
  
  // Move back through the string until you don't hit whitespace.
  var end = str.length;
  while ((end > 0) && ( (str.charAt(end-1) == ' ') || (str.charAt(end-1) == '\n') || (str.charAt(end-1) == '\r') || (escape(str.charAt(end-1))=='%A0') || (str.charAt(start) == escape('&nbsp;')) ) ) --end;
  
  // If all whitespace, return the null string.
  if (start>end) {return "";}

  // Else return the subtring that isn't whitespace.
  else {return str.substring(start, end);}
return true;}


// This function converts a given string to uppercase.
function upper(str) {return str.toUpperCase();}


// This function truncates a given string to a given length.
function truncate(str,length){
  if(str.length && str.length>length) return str.substr(0,length);
}