[英]How can I use a variable as an index inside of an object? (Javascript)
我正在尝试使用变量 appetizer、main 和甜点作为数组的索引,但我不知道如何做到这一点。 这是在第 49 行。
var menu = {
_courses: {
appetizers: [],
mains: [],
desserts: []
},
get appetizers() {
return this._courses.appetizers;
},
get mains() {
return this._courses.mains;
},
get desserts() {
return this._courses.desserts;
},
set appetizers(appetizers) {
this.courses.desserts = desserts;
},
set mains(mains) {
this.mains = mains;
},
set desserts(desserts) {
this.desserts = desserts;
},
get courses() {
return {
appetizers,
mains,
desserts,
};
},
addDishToCourse (courseName, dishName, dishPrice) {
const dish = {
food: courseName,
name: dishName,
price: dishPrice,
};
return this._courses[courseName].push(dish);
},
getRandomDishFromCourse: function(courseName) {
var dishes = this._courses[courseName];
if (dishes !== undefined) {
var randomIndex = Math.floor(Math.random() * dishes.length);
return randomIndex;
}
},
generateRandomMeal: function() { //This is the problem.
var appetizer = this.getRandomDishFromCourse('appetizers');
var main = this.getRandomDishFromCourse('mains');
var dessert = this.getRandomDishFromCourse('dessert');
return 'Your meal is ' + appetizer + ', ' + main + ', and ' + dessert + '. The total price is $' +/* this.dish.price */ 8 + '.';
}
};
menu.addDishToCourse('appetizers', 'Bread Loaf', 4.25);
menu.addDishToCourse('appetizers', 'Caesar Salad', 3.50);
menu.addDishToCourse('appetizers', 'Small Soup', 4.50);
menu.addDishToCourse('mains', 'Steak Dinner', 20.00);
menu.addDishToCourse('mains', 'spaghetti', 16.00);
menu.addDishToCourse('mains', 'Turkey Dinner', 18.99);
menu.addDishToCourse('desserts', 'Icecream', 5.99);
menu.addDishToCourse('desserts', 'Cookies', 5.99);
menu.addDishToCourse('desserts', 'Jello', 5.99);
var meal = menu.generateRandomMeal();
console.log(meal);
我曾尝试使用此代码:
this.appetizers[appetizer]
this.mains[main]
this.desserts[dessert]
但这只是返回 Object 对象代替索引号。
你的getRandomDishFromCourse
从传递的courseName
选择一个随机索引,但它只返回索引 - 它应该通过return dishes[randomIndex];
返回一个dish对象return dishes[randomIndex];
.
菜品返回后,在generateRandomMeal
,您需要选择每个菜品的name
属性进行打印,并将所有price
相加得到总价:
getRandomDishFromCourse: function(courseName) {
var dishes = this._courses[courseName];
if (dishes !== undefined) {
var randomIndex = Math.floor(Math.random() * dishes.length);
return dishes[randomIndex];
}
},
generateRandomMeal: function() { //This is the problem.
var appetizer = this.getRandomDishFromCourse('appetizers');
var main = this.getRandomDishFromCourse('mains');
var dessert = this.getRandomDishFromCourse('desserts');
return 'Your meal is ' + appetizer.name + ', ' + main.name + ', and ' + dessert.name +
'. The total price is $' + (appetizer.price + main.price + dessert.price).toFixed(2)
}
var menu = { _courses: { appetizers: [], mains: [], desserts: [] }, get appetizers() { return this._courses.appetizers; }, get mains() { return this._courses.mains; }, get desserts() { return this._courses.desserts; }, set appetizers(appetizers) { this.courses.desserts = desserts; }, set mains(mains) { this.mains = mains; }, set desserts(desserts) { this.desserts = desserts; }, get courses() { return { appetizers, mains, desserts, }; }, addDishToCourse(courseName, dishName, dishPrice) { const dish = { food: courseName, name: dishName, price: dishPrice, }; return this._courses[courseName].push(dish); }, getRandomDishFromCourse: function(courseName) { var dishes = this._courses[courseName]; if (dishes !== undefined) { var randomIndex = Math.floor(Math.random() * dishes.length); return dishes[randomIndex]; } }, generateRandomMeal: function() { //This is the problem. var appetizer = this.getRandomDishFromCourse('appetizers'); var main = this.getRandomDishFromCourse('mains'); var dessert = this.getRandomDishFromCourse('desserts'); return 'Your meal is ' + appetizer.name + ', ' + main.name + ', and ' + dessert.name + '. The total price is $' + (appetizer.price + main.price + dessert.price).toFixed(2) } }; menu.addDishToCourse('appetizers', 'Bread Loaf', 4.25); menu.addDishToCourse('appetizers', 'Caesar Salad', 3.50); menu.addDishToCourse('appetizers', 'Small Soup', 4.50); menu.addDishToCourse('mains', 'Steak Dinner', 20.00); menu.addDishToCourse('mains', 'spaghetti', 16.00); menu.addDishToCourse('mains', 'Turkey Dinner', 18.99); menu.addDishToCourse('desserts', 'Icecream', 5.99); menu.addDishToCourse('desserts', 'Cookies', 5.99); menu.addDishToCourse('desserts', 'Jello', 5.99); var meal = menu.generateRandomMeal(); console.log(meal);
( toFixed(2)
需要在 total 之后以避免浮点问题)
您需要使用索引来访问数组中的项目。 你现在拥有它的方式只会打印随机索引。
var menu = { _courses: { appetizers: [], mains: [], desserts: [] }, get appetizers() { return this._courses.appetizers; }, get mains() { return this._courses.mains; }, get desserts() { return this._courses.desserts; }, set appetizers(appetizers) { this.courses.desserts = desserts; }, set mains(mains) { this.mains = mains; }, set desserts(desserts) { this.desserts = desserts; }, get courses() { return { appetizers: this.appetizers, mains: this.mains, desserts: this.desserts, }; }, addDishToCourse(courseName, dishName, dishPrice) { const dish = { food: courseName, name: dishName, price: dishPrice, }; return this._courses[courseName].push(dish); }, getRandomDishFromCourse: function(courseName) { var dishes = this._courses[courseName]; if (dishes !== undefined) { var randomIndex = Math.floor(Math.random() * dishes.length); return randomIndex; } }, generateRandomMeal: function() { //This is the problem. var appetizer = this.appetizers[this.getRandomDishFromCourse('appetizers')]; var main = this.mains[this.getRandomDishFromCourse('mains')]; var dessert = this.desserts[this.getRandomDishFromCourse('desserts')]; return 'Your meal is ' + appetizer.name + ', ' + main.name + ', and ' + dessert.name + '. The total price is $' + /* this.dish.price */ 8 + '.'; } }; menu.addDishToCourse('appetizers', 'Bread Loaf', 4.25); menu.addDishToCourse('appetizers', 'Caesar Salad', 3.50); menu.addDishToCourse('appetizers', 'Small Soup', 4.50); menu.addDishToCourse('mains', 'Steak Dinner', 20.00); menu.addDishToCourse('mains', 'spaghetti', 16.00); menu.addDishToCourse('mains', 'Turkey Dinner', 18.99); menu.addDishToCourse('desserts', 'Icecream', 5.99); menu.addDishToCourse('desserts', 'Cookies', 5.99); menu.addDishToCourse('desserts', 'Jello', 5.99); //console.log(JSON.stringify(menu, null, 4)); console.log(menu.generateRandomMeal());
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