what does myfunction(<?=$num?>) do in html code example

Example: functions in javascript

function myFunction(var1, var2) {
  return var1 * var2;
}
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How to create a function in javascriptJavascript By TechWhizKid on Apr 5 2020
function addfunc(a, b) {
  return a + b;
  // standard long function
}

addfunc = (a, b) => { return a + b; }
// cleaner faster way creating functions!