Question

该脚本的工作原理是要求用户添加或删除数组中的项目。然后要求继续这个循环。这里的问题是我的脚本似乎不匹配我的用户的输入（removeItem）与列表中的项目（myList [i]）。我很遗憾为什么这不匹配。

// new method for removing specific items from a list
Array.prototype.remove = function(from,to) {
    var rest = this.slice((to || from) + 1 || this.length);
    this.length = from < 0 ? this.length + from : from;
    return this.push.apply(this, rest);
};

printList = function() {
    var listLength = myList.length;
    for (i = 0; i < listLength; i++) {
        document.write(i + ":");
        document.write(myList[i] + "<br/>");
    };
    document.write("<br/><br/>");
};

// initial list
var myList = new Array ();
if (myList.length === 0) {
    document.write("I have " + myList.length + " item in my list. It is: <br/>");
}
else {
    document.write("I have " + myList.length + " items in my list. They are: <br/>");
}
printList();

var continueAdding = "yes";
var askToContinue = "";

while (continueAdding === "yes") {
    // loop
    var askUser = prompt("What do you want to [A]dd or [R]emove an item to your inventory?").toUpperCase();
    switch (askUser) {
        case "A": { // add an user specified item to the list
            var addItem = prompt("Add something to the list");
            myList.push(addItem);
            printList();
            break;
        }
        case "R": { // remove an user specified item from the list
            var removeItem = prompt("what do you want to remove?"); 
            var listLength = myList.length;
            for (i = 0; i < listLength; i++) {
                if (removeItem === myList[i]) {
                    document.write("I found your " + removeItem + " and removed it.<br/>");
                    myList.remove(i);
                }
                else {
                    document.write(removeItem + " does not exist in this list.<br/>");
                    break;
                }
                if (myList.length === 0) {
                    myList[0] = "Nada";
                }
            };
            printList();
            break;
        }
        default: {
            document.write("That is not a proper choice.");
        }
    };

    askToContinue = prompt("Do you wish to continue? [Y]es or [N]o?").toUpperCase(); // ask to continue
    if (askToContinue === "Y") {
        continueAdding = "yes";
    }
    else {
        continueAdding = "no";
    }
}

Answer 1

你的循环从不允许它遍历所有项目，因为如果项目不匹配，它会在第一次迭代时中断。

break语句应位于if块中，而不是else块中 - 请改用：

for (i = 0; i < listLength; i++) {
    if (removeItem === myList[i]) {
        document.write("I found your " + removeItem + " and removed it.<br/>");
        myList.remove(i);
        break;
    }
    else {
        document.write(removeItem + " does not exist in this list.<br/>");
    }
};

if (myList.length === 0) {
    myList[0] = "Nada";
}

另外，请注意，它正在寻找完全匹配，区分大小写，相同的标点符号以及所有内容。如果你想让它更宽松，你需要修改脚本，将两个字符串转换为小写并删除标点符号，然后再进行比较。

编辑：刚注意到别的东西 - 测试空列表需要在循环外完成。我更新了上面的代码以反映这一点。

尝试添加和删除数组中的项目

1 个答案: