如果这个标题没有意义,让我详细说明一下。
我有两个对象,一个称为区域,一个称为敌人。
每个区域都有自己的敌人,所以我为每个区域制作了敌人原型。
接下来,我对每个区域原型做了一个array.push();
功能,因此如果用户单击按钮,他们将看到他们基本上可以探索的"区域"列表。
给我错误的主要部分是如果我尝试任何功能,例如alert(areas[0].enemies[0].name);
如何使用按钮显示特定的敌人名称?
请不要查询
function area(name, enemies) {
this.name = name;
this.enemies = enemies;
}
function enemy(name, type) {
this.name = name;
this.type = type;
}
var cave = new area("Cave", {
bat: new enemy("Bat", "Flying"),
snake: new enemy("Snake", "Ground"),
});
var forest = new area("Forest", {
bear: new enemy("Bear", "Animal"),
coyote: new enemy("Coyote", "Wolf"),
});
areas = [];
areas.push(cave, forest);
var thatBtn = document.getElementById('thatBtn'),
display = document.getElementById('display');
thatBtn.addEventListener('click', function() {
for (i = 0; i < areas.length; i++) {
var li = document.createElement('li'),
liBtn = document.createElement('button');
liBtn.textContent = areas[i].name;
li.appendChild(liBtn);
display.appendChild(li);
liBtn.addEventListener('click', function() {
for (j = 0; j < areas.length; j++) {
if (areas[j].name == event.target.textContent) {
alert(areas[j].name);
for (k = 0; k < Object.keys(areas[j].enemies).length; k++) {
alert(areas[j].enemies[k].name);
}
}
}
});
}
});
<button id="thatBtn">click here</button>
<ul id="display">
</ul>
它给你一个错误,因为areas[0].enemies
不是一个数组——它是一个对象。
{
bat: new enemy("Bat", "Flying"),
snake: new enemy("Snake", "Ground"),
}
将其更改为
for(var key in areas[j].enemies) {
alert(areas[j].enemies[key].name);
}
enemies
是一个对象而不是数组,所以你需要遍历keys
并从那里而不是从索引中获取,只是用它更新了您的代码段,但是代码可以更好。
function area(name, enemies){
this.name = name;
this.enemies = enemies;
}
function enemy(name, type){
this.name = name;
this.type = type;
}
var cave = new area ("Cave", {
bat: new enemy("Bat", "Flying"),
snake: new enemy("Snake", "Ground"),
});
var forest = new area ("Forest", {
bear: new enemy("Bear", "Animal"),
coyote: new enemy("Coyote", "Wolf"),
});
areas = [];
areas.push(cave, forest);
var thatBtn = document.getElementById('thatBtn'),
display = document.getElementById('display');
thatBtn.addEventListener('click', function(){
for(i=0; i < areas.length; i++){
var li = document.createElement('li'),
liBtn = document.createElement('button');
liBtn.textContent = areas[i].name;
li.appendChild(liBtn);
display.appendChild(li);
liBtn.addEventListener('click', function(){
for(j=0; j < areas.length; j++){
if (areas[j].name == event.target.textContent){
alert(areas[j].name);
var keys = Object.keys(areas[j].enemies);
for(k=0; k < Object.keys(areas[j].enemies).length; k++){
alert(areas[j].enemies[keys[k]].name);
}
}
}
});
}
});
<button id="thatBtn">click here</button>
<ul id="display">
</ul>
将敌人添加为数组,无需在对象中使用"命名键">
function area(name, enemies){
this.name = name;
this.enemies = enemies;
}
function enemy(name, type){
this.name = name;
this.type = type;
}
var cave = new area ("Cave", [
new enemy("Bat", "Flying"),
new enemy("Snake", "Ground"),
]);
var forest = new area ("Forest",[
new enemy("Bear", "Animal"),
new enemy("Coyote", "Wolf"),
]);
areas = [];
areas.push(cave, forest);
var thatBtn = document.getElementById('thatBtn'),
display = document.getElementById('display');
thatBtn.addEventListener('click', function(){
for(i=0; i < areas.length; i++){
var li = document.createElement('li'),
liBtn = document.createElement('button');
liBtn.textContent = areas[i].name;
li.appendChild(liBtn);
display.appendChild(li);
liBtn.addEventListener('click', function(){
for(j=0; j < areas.length; j++){
if (areas[j].name == event.target.textContent){
alert(areas[j].name);
for(k=0; k < Object.keys(areas[j].enemies).length; k++){
alert(areas[j].enemies[k].name);
}
}
}
});
}
});
<button id="thatBtn">click here</button>
<ul id="display">
</ul>
您的主要问题在这里:
for(k=0; k < Object.keys(areas[j].enemies).length; k++){
alert(areas[j].enemies[k].name);
}
表达式Object.keys(areas[j].enemies)
返回对象属性数组,但随后您尝试使用k而不是属性名称循环访问对象。
由于Object.keys返回一个数组,因此您可以使用数组方法,因此将循环更改为:
Object.keys(areas[j].enemies).forEach(function(name) {
alert(areas[j].enemies[name]);
});
您有一个次要问题,即您没有声明循环中使用的计数器(i、j和k(,因此它们在代码运行时成为全局变量。声明它们如下:
for (var i=0; i < areas.length; i++) {