Google Chrome
1-Click the Chrome menu icon Chrome menu on the browser toolbar.
2-Select Settings.
3-On the "Settings" page, click the Show advanced settings... link.
4-In the "Privacy" section, click Content settings...
5-Select Allow all sites to run JavaScript (recommended) in the "JavaScript" section.
6-Click Done.
Internet Explorer
1-Tools → Internet Options from the menu.
2-Select Security tab from the dialog box.
3-Click the Custom Level button.
4-Scroll down till you find Scripting option.
5-Select Enable radio button under Active scripting.
6-Finally click OK and come out
Firefox
1-Open a new tab → type about: config in the address bar.
2-Then you will find the warning dialog. Select I’ll be careful, I promise!
3-Then you will find the list of configure options in the browser.
4-In the search bar, type javascript.enabled.
5-There you will find the option to enable or disable javascript by right-clicking on the value of that option → select toggle.
If javascript.enabled is true; it converts to false upon clicking toogle. If javascript is disabled; it gets enabled upon clicking toggle.
Opera
1-Follow Tools → Preferences from the menu.
2-Select Advanced option from the dialog box.
3-Select Content from the listed items.
4-Select Enable JavaScript checkbox.
5-Finally click OK and come out.