I would like to test a website with an older version of JavaScript to make sure that we are not using any new methods or plugins that breaks in old browsers. Is there any way whether to emulate or to force the browser to use older javascript versions such as the ones here: JavaScript Version History
From experience this gets messy. You are best using free software such as https://www.virtualbox.org/ which allows you to setup up an actual old machine running an old browser (as many as the test system can take). That way you replicate the precise test environment. You should be able to get various old OS machine installs cheaply as they have no value.