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Frontend question · JavaScript › this & binding

What does this log?

"use strict";
function show() {
  return this;
}
const obj = { show };
console.log(obj.show() === obj, show(), show.call(42));
true undefined 42

The answer is true undefined 42.
• obj.show() uses implicit binding, so this is obj.
• A plain call show() in strict mode gives undefined, not the global object.
• In strict mode, call(42) passes the primitive 42 as it is.

The tempting option "true undefined [Number: 42]" is wrong because of strict mode. Only sloppy (non-strict) mode would box 42, which means wrap it in a Number object.