JavaScript in the Browser

Form Source Code

<form id="everything">      <!-- A one-of-everything HTML form... -->
 <table border="border" cellpadding="5">   <!-- in a big HTML table -->
     <td>Username:<br/>[1]<input type="text" name="username" size="15"/></td>
     <td>Password:<br/>[2]<input type="password" name="password" size="15"/></td>
     <td rowspan="4">Input Events[3]<br/>
       <textarea name="textarea" rows="20" cols="28"></textarea></td>
     <td rowspan="4" align="center" valign="center">
       [9]<input type="button" value="Clear" name="clearbutton"/><br/>
       [10]<input type="submit" name="submitbutton" value="Submit"/><br/>
       [11]<input type="reset" name="resetbutton" value="Reset"/></td></tr>
     <td colspan="2">
       Filename: [4]<input type="file" name="file" size="15"/></td></tr>
     <td>My Computer Peripherals:<br/>
       [5]<input type="checkbox" name="extras" value="burner"/>DVD Writer<br/>
       [5]<input type="checkbox" name="extras" value="printer"/>Printer<br/>
       [5]<input type="checkbox" name="extras" value="card"/>Card Reader</td>
     <td>My Web Browser:<br/>
       [6]<input type="radio" name="browser" value="ff"/>Firefox<br/>
       [6]<input type="radio" name="browser" value="ie"/>Internet Explorer<br/>
       [6]<input type="radio" name="browser" value="other"/>Other</td></tr>
     <td>My Hobbies:[7]<br/>
       <select multiple="multiple" name="hobbies" size="4">
         <option value="programming">Hacking JavaScript</option>
         <option value="surfing">Surfing the Web</option>
         <option value="caffeine">Drinking Coffee</option>
         <option value="annoying">Annoying my Friends</option>
     <td align="center" valign="center">My Favorite Color:<br/>[8]
       <select name="color">
         <option value="red">Red</option> <option value="green">Green</option>
         <option value="blue">Blue</option>  <option value="white">White</option>
         <option value="violet">Violet</option>  <option value="peach">Peach</option>

<div align="center">        <!-- Another table--the key to the one above -->
  <table border="4" bgcolor="pink" cellspacing="1" cellpadding="4">
      <td align="center"><b>Form Elements</b></td>
      <td>[1] Text</td>  <td>[2] Password</td>  <td>[3] Textarea</td>
      <td>[4] FileU</td> <td>[5] Checkbox</td></tr>
      <td>[6] Radio</td>  <td>[7] Select (list)</td>
      <td>[8] Select (menu)</td>  <td>[9] Button</td>
      <td>[10] Submit</td>  <td>[11] Reset</td></tr>

<script src="18-1.js"></script>
// This generic function appends details of an event to the big Textarea
// element in the form above. It is called from various event handlers.
function report(element, event) {
    if ((element.type == "select-one") || (element.type == "select-multiple")){
        value = " ";
        for(var i = 0; i < element.options.length; i++)
            if (element.options[i].selected) 
                value += element.options[i].value + " ";
    else if (element.type == "textarea") value = "...";
    else value = element.value;
    var msg = event + ": " + + ' (' + value + ')\n';
    var t = element.form.textarea;
    t.value = t.value + msg;

// This function adds a bunch of event handlers to every element in a form.
// It doesn't bother checking to see if the element supports the event handler,
// it just adds them all. Note that the event handlers call report().
// We're defining event handlers by assigning functions to the
// properties of JavaScript objects rather than by assigning strings to
// the attributes of HTML elements.
function addhandlers(f) {
    // Loop through all the elements in the form
    for(var i = 0; i < f.elements.length; i++) {
        var e = f.elements[i];
        e.onclick = function() { report(this, 'Click'); }
        e.onchange = function() { report(this, 'Change'); }
        e.onfocus = function() { report(this, 'Focus'); }
        e.onblur = function() { report(this, 'Blur'); }
        e.onselect = function() { report(this, 'Select'); }

    // Define some special-case event handlers for the three buttons:
    f.clearbutton.onclick = function() {
        this.form.textarea.value=''; report(this,'Click');
    f.submitbutton.onclick = function () {
        report(this, 'Click'); return false;
    f.resetbutton.onclick = function() {
        this.form.reset(); report(this, 'Click'); return false;
// Finally, activate our form by adding all possible event handlers!

José M. Vidal .

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