Introduction.  So now that we have talked about obtaining information from the controls on forms we also need to develop approaches to using JavaScript to put information into the controls on the form from the code.  As you'd expect, this process differs somewhat depending on what sort of control you are working with.

Our first example will be a modification of the temperature conversion program where we use text boxes rather than prompt( ) and alert( ) boxes.  You should copy this code into a file called FToCTextboxes.html.

window.document.ConvertTemp.txtCelsius.value = CDegrees;

This same approach works for both textboxes and textareas.

Resetting Defaults.  Now we are going to work with the three other basic control types in forms,

1. checkboxes

2. radio buttons

3. select/drop down boxes

Each of these requires a somewhat different approach to be assigned values within the code.

First we will give the code which should be put in a file called ResetTheDefaults.html.

// resetting the defaults for the check boxes
window.document.ResetDefaults.chkProgramming.checked = true;
window.document.ResetDefaults.chkAnalysisDesign.checked = false;
window.document.ResetDefaults.chkSysAd.checked = true;

These statements just re-assign the checked property on each checkbox control.

To reset the radio buttons just requires one statement because all three are in a grouping.  The code to reset the radio buttons is

// resetting the default for the radio buttons
// setting default use level to intermittent
window.document.ResetDefaults.rbFreq[1].checked = true;

Remember the radio buttons are considered to be in the same array and setting one to be true requires the others to be false.  It is also important to remember the array numbering starts at 0.

Finally, the code for resetting the select/drop down box requires just one statement because only one option in the box can be selected.  The others are automatically unselected.  The code for resetting the select/drop down box is

// resetting the select/drop down box
// setting default type of use to Games
window.document.ResetDefaults.cboType.options[2].selected = true;

Again, an array is used to determine which option is selected.

Now you should be able to set the values of controls in a form whenever you want.