Its not required no.
Is type= text/javascript necessary. It is a set of elements of 16-bit unsigned. The type attribute is unnecessary for JavaScript resources. The part of the HTML Living Standard youre interested in is The linkelement which states.
The type attribute gives the language of the script or format of the data. Using the scripttag to include an external JavaScript file. The TYPEtextjavascript in the script tag is necessary to bring the source code up to standards.
The type attribute gives the language of the script or format of the data. An audio audio type. If the script is blocked an error is sent to the element if not a load event is sent.
The default which is used if the attribute is absent is textjavascript. To include an external JavaScript file we can use the script tag with the attribute src. The charset parameter must not be specified.
A video type video. Is typetextjavascript necessary. From line 10 column 146.
The script will work without it but I like tory and be as standards-compliant as I can. The typeattribute gives the MIME type of the linked resource. The default which is used if the attribute is absent is textjavascript.