From the main menu bar along the top of the window, select "Tools > Internet Options"

Then select the tab called "Security"

Click on the button names "Custom Level..."

Scroll down to the heading "Scripting"

Ensure that the selected option is "Enabled" under the sub-heading "Active Scripting"

Then click "OK" to save your changes and restart Internet Explorer

From the main menu bar along the top of the window, select "Tools > Options..."

Then select the tab called "Content"

Make sure the box "Enable JavaScript" is checked

Then click "OK" to save your changes and restart Firefox

From the main menu bar along the top of the window, select "Edit > Preferences..."

Then select the tab called "Security"

You will then see a few tick boxes under the heading "Web Content", with one being labelled, "Enable JavaScript"

If this box is not ticked, click on it to tick it, and click "OK", and restart Safari

From the main menu bar along the top of the window, select "Tools > Preferences..."

Then select the tab named "Advanced"

Select "Content" from the list down the left-hand side

Make sure that the "Enable JavaScript" option is ticked

Then click "OK" to save your changes