Javascript函数作为参数-浏览器兼容性

Question

I know that the ability to pass function names as parameters is handled by almost all modern browsers, but I'm wondering about older browsers compatibility:

1. What was the first version of JavaScript/ECMAScript that supported it? Was it supported since the first days of JavaScript? (That would surprise me)
2. What were the versions of each of the major browsers (Google Chrome, Firefox, IE, Safari, Opera, etc.) that first supported it?

Answer 1

据我所知，函数始终是对象，并且对象始终可以作为参数传递。

Answer 2

The use of anonymous functions as expressions and the passing of the names of declared functions has been available on all JavaScript supporting browsers since before Internet Explorer 6.

The first documentation I could find on it is ECMA-262 , which dates as far back as 1997.

If you're talking about full support, old versions of IE ( even up to IE8 ), suffered from a variable leak in named function expressions , where the name of the function expression becomes defined and set in the parent scope, as if it was actually a declared function .

// Assuming old JScript engine
typeof foo; // "undefined", expected, it's not been defined yet
bar; // defined as if hoisted function declaration, unexpected

var foo = function bar() {};
foo; // as expected
bar; // identical to foo, not expected

foo === bar; // false, they're actually different function objects in memory

Answer 3

What was the first version of JavaScript/ECMAScript that supported it? Was it supported since the first days of JavaScript? (That would surprise me)

1

It is a core language feature.

What were the versions of each of the major browsers (Google Chrome, Firefox, IE, Safari, Opera, etc.) that first supported it?

The earliest JS supporting browsers support it.