In javascript, how to get a class name from a td cell?

example:

<td class="ColumnHeader" style="text-align:right;" >

class "ColumnHeader" is a class inside css, how could i retrieve it from css and changed the width size in javascript?

In javascript, how to get a class name from a td cell?

example:

<td class="ColumnHeader" style="text-align:right;" >

class "ColumnHeader" is a class inside css, how could i retrieve it from css and changed the width size in javascript?

• javascript
• html
• css

• Are you trying to modify a stylesheet with JS or modify the class attribute of a DomNode? – fnp Commented Nov 15, 2011 at 2:36

2 Answers 2

Select all the <td> elements via getElementsByTagName() and iterate over them looking for the className:

var tds = document.getElementsByTagName("td");
for (var i = 0; i<tds.length; i++) {

  // If it currently has the ColumnHeader class...
  if (tds[i].className == "ColumnHeader") {
    // Set a new width
    tds[i].style.width = new_width;

    // Or set a different class which defines the width
    tds[i].className = "someOtherClass";
  }
}

You can't really change the width of the css class programatically, but you can change it on the element:

td.style.width = newWidth;

To get the class name from an element, use:

var className = td.className;