循环中的javarscript“可变变量可以从闭包中获取”

Question

Im trying to assign a function to every button inside an array.

to simplify the problem i have exchanged the functionality of that function with a simple console.log

When one of the buttons is clicked the console is supposed to say "button number" and then the according button number (1, 2, 3...) Instead it always returns the maximum button number.

        function buttoncount(){
            dbuttons = document.getElementsByClassName("deletebutton");
            for(var ii = 0; ii< dbuttons.length; ii++){
                dbuttons[ii].onclick = function (){
                    console.log("button number"+ii);
                }
            }
        }

thanks in advance

Answer 1

You'd have to ensure that separate closures are caught for consecutive buttons. One of the ways is always to wrap the actual function within another one that is immediately executed.

    function buttoncount(){
        dbuttons = document.getElementsByClassName("deletebutton");
        for(var ii = 0; ii< dbuttons.length; ii++){
            dbuttons[ii].onclick = (function (x){
                return function() {
                  console.log("button number"+x);
                }
            }(ii));
        }
    }