Hello leftblank15,
JavaScript still plays a big role in browsing the web today, you can find more info on JavaScript and how to disable it here. The article will list two solutions to blocking JavaScript on specified domains. You can click or tap here to check if JavaScript is enabled on your web browsers. Regarding your question about if a bad site containing JavaScript infection your mac, of course a website running JavaScript could still infect your machine however unlikely if you are browsing trusted web sites. You can click or tap here to check a websites reputation.