JavaScript and Ajax for the Web: Visual QuickStart Guide, Seventh Edition

The onfocus event

Sometimes you’ll have a form field on a page with data that you want to display as part of the form, without the user being able to modify that field. You can use the readonly HTML attribute to try to keep users out, but not all browsers support it. Scripts 9.18 and 9.19 show how to use the onfocus event to bump users right back out of this field, on the off chance they made it to where they shouldn’t be.

• allTags[i].onfocus = function() {
    this.blur();
  }

When the user attempts to enter this field, the focus (in this case the active field) will automatically be kicked right back out again (Figure 9.8). This happens because the onfocus event handler is set to call an anonymous function (one without a name) that does just one thing: ...