Should one avoid declaring functions within functions (except for intentional closures)?

Question

{Code...} The function test is declared each time it is clicked, and then the click callback is executed and GCed. If the dom is clicked more than once, then each click callback has one more function declaration. I remember that it is not in the jshint specification. Allow function declarations to be written into loops. The current situation is not...

过去多啦不再A梦 · Answer

There is a difference between a loop and a function.

The loop is not an independent scope, so declaring the function in it will be declared in advance, but not in the function. jshint prevents duplicate definitions.

function a() {
    function b() {
    }
}

b will only be declared when function a is executed, and if there is no external reference pointing to b, it will be destroyed after the function executes the next round of recycling.

In fact there is not much difference.

世界只因有你 · Answer

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

$('.dom').on('click', function () {
  test('abc')
});

Test is thrown away after use, it will not be irrecyclable.

为情所困 · Answer

If it is executed only once, it can be like this:

var elem = $('.dom'); 
elem.on('click', (function() {
    return function foo(e) {
        // do something...
        elem.off('click', foo);
    };
}()));

The defined foo will not affect the outside world, uninstall it immediately after use and wait for recycling.
Clean, hiding the merit and fame