According to Crockford[0], Netscape called it LiveScript, originally. In their attempt to 'destroy Microsoft', they teamed up with Sun. One of Sun's original goals with Java was making it the client-side scripting language for the browser. However, Netscape had LiveScript. Apparently the negotiations almost broke down over this point.
In an enlightened moment, (probably) Marc Andreessen proposed renaming LiveScript to JavaScript (despite the fact that the languages have very little in common), and joy was had. Sun got the JavaScript trademark (and passed it on to Oracle), and Netscape got a perpetual exclusive license to use it.
When JavaScript was standardized to avoid Embrace, Extend, Extinguish, Netscape refused to share its license, and so the official language was renamed to ECMAScript, after the standards body. When Sun was bought by Oracle, it also got the trademark, and presumably, Mozilla inherited the exclusive license from Netscape.
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