javascript - 在 for-in 循环中传递按钮单击事件上的键时获取单词 "extend"

Question

我有一个如下所示的 json:

contacts = [{"id":"0001","title":"Mr","name_first":"Bob","name_last":"Edwards","address1":"2 ford road","address2":null,"address3":null,"town":"Bedford","county":"Bedfordshire","postcode":"Mk16hd","telephone1":"01827485999","telephone2":null,"email":"bob@email.com"},
{"id":"8003","title":"Mr","name_first":"Joe","name_last":"Bloggs","address1":"186 Bath Road","address2":null,"address3":null,"town":null,"county":null,"postcode":null,"telephone1":"01827485648","telephone2":null,"email":"joe@email.com"},
{"id":"R005","title":"Mr","name_first":"Foo","name_last":"Bar","address1":null,"address2":null,"address3":null,"town":null,"county":null,"postcode":null,"telephone1":"01827485647","telephone2":null,"email":"foo@email.com"}];

然后我像这样循环，为每个按钮创建一个按钮:

for (var key in contacts) { 
    if (contacts.hasOwnProperty(key)) {
        var contact = contacts[key];

        var button = document.createElement('button');
        button.innerHTML = '<span class="left-body">Edit</span>';
        button.onclick = function() { editContact(key); return false; };
    }
}

单击每个按钮时，我会在 editContact() 函数中得到“extend”一词作为索引值:

function editContact (index) {
    console.log(index);
    return false;
}

问:这是什么？如何设置它以便将每个 json 项目的 key 获取到 editContact() 函数中？

Answer 1

因为关闭了

for (var key in contacts) { 
    if (contacts.hasOwnProperty(key)) {
        var contact = contacts[key];

        var button = document.createElement('button');
        button.innerHTML = '<span class="left-body">Edit</span>';
        button.onclick = (function(key){
            return function() { editContact(key); return false; };
        })(key);
    }
}

演示:Fiddle