js问题,浏览器报错Cannot read property 'id' of undefined
我在编程时产生如下错误:
var buttons = main.getElementsByTagName("input");
for (i = 0; i < buttons.length; i++) {
buttons[i].onclick = function () { addItem(buttons[i].id, "sides"); };//报错rt
}
var buttons = main.getElementsByTagName("input");
for (i = 0; i < buttons.length; i++) {
var id = buttons[i].id;
buttons[i].onclick = function () { addItem(id, "sides"); };//正常
}
这个是什么原理,没弄明白