严格模式下匿名函数的参数

Question

When running this snippet

"use strict";
(new function test(a) { console.log(a); })(window);

Why do I get undefined for a ? Why isn't the window passed to the anonymous function?

Answer 1

What you're doing is (almost) equivalent to this:

"use strict";

function test(a) {
  console.log(a);
}

val t = new test(undefined);

t(window);

Just remove the new keyword:

"use strict";
(function test(a) { console.log(a); })(window);