【发布时间】：2020-06-10 16:10:34
【问题描述】：
我看到一个这样的函数：
getDish(id: number): Dish {
return DISHES.filter((dish) => (dish.id === id))[0];
}
但我不明白为什么它在过滤功能后使用[0]？我的意思是filter 的返回值是什么样的，为什么它只指定索引0？
编辑：这是DISHES：
export const DISHES: Dish[] = [
{
id: 0,
name: 'Uthappizza',
image: '/assets/images/uthappizza.png',
category: 'mains',
label: 'Hot',
price: '4.99',
featured: true,
description: 'A unique combination of Indian Uthappam (pancake) and Italian pizza, topped with Cerignola olives, ripe vine cherry tomatoes, Vidalia onion, Guntur chillies and Buffalo Paneer.',
comments: [
{
rating: 5,
comment: "Imagine all the eatables, living in conFusion!",
author: "John Lemon",
date: "2012-10-16T17:57:28.556094Z"
},
{
rating: 4,
comment: "Sends anyone to heaven, I wish I could get my mother-in-law to eat it!",
author: "Paul McVites",
date: "2014-09-05T17:57:28.556094Z"
},
{
rating: 3,
comment: "Eat it, just eat it!",
author: "Michael Jaikishan",
date: "2015-02-13T17:57:28.556094Z"
},
{
rating: 4,
comment: "Ultimate, Reaching for the stars!",
author: "Ringo Starry",
date: "2013-12-02T17:57:28.556094Z"
},
{
rating: 2,
comment: "It's your birthday, we're gonna party!",
author: "25 Cent",
date: "2011-12-02T17:57:28.556094Z"
}
]
},
{
id: 1,
name: 'Zucchipakoda',
image: '/assets/images/zucchipakoda.png',
category: 'appetizer',
label: '',
price: '1.99',
featured: false,
description: 'Deep fried Zucchini coated with mildly spiced Chickpea flour batter accompanied with a sweet-tangy tamarind sauce',
comments: [
{
rating: 5,
comment: "Imagine all the eatables, living in conFusion!",
author: "John Lemon",
date: "2012-10-16T17:57:28.556094Z"
},
{
rating: 4,
comment: "Sends anyone to heaven, I wish I could get my mother-in-law to eat it!",
author: "Paul McVites",
date: "2014-09-05T17:57:28.556094Z"
},
{
rating: 3,
comment: "Eat it, just eat it!",
author: "Michael Jaikishan",
date: "2015-02-13T17:57:28.556094Z"
},
{
rating: 4,
comment: "Ultimate, Reaching for the stars!",
author: "Ringo Starry",
date: "2013-12-02T17:57:28.556094Z"
},
{
rating: 2,
comment: "It's your birthday, we're gonna party!",
author: "25 Cent",
date: "2011-12-02T17:57:28.556094Z"
}
]
},
{
id: 2,
name: 'Vadonut',
image: '/assets/images/vadonut.png',
category: 'appetizer',
label: 'New',
price: '1.99',
featured: false,
description: 'A quintessential ConFusion experience, is it a vada or is it a donut?',
comments: [
{
rating: 5,
comment: "Imagine all the eatables, living in conFusion!",
author: "John Lemon",
date: "2012-10-16T17:57:28.556094Z"
},
{
rating: 4,
comment: "Sends anyone to heaven, I wish I could get my mother-in-law to eat it!",
author: "Paul McVites",
date: "2014-09-05T17:57:28.556094Z"
},
{
rating: 3,
comment: "Eat it, just eat it!",
author: "Michael Jaikishan",
date: "2015-02-13T17:57:28.556094Z"
},
{
rating: 4,
comment: "Ultimate, Reaching for the stars!",
author: "Ringo Starry",
date: "2013-12-02T17:57:28.556094Z"
},
{
rating: 2,
comment: "It's your birthday, we're gonna party!",
author: "25 Cent",
date: "2011-12-02T17:57:28.556094Z"
}
]
},
{
id: 3,
name: 'ElaiCheese Cake',
image: '/assets/images/elaicheesecake.png',
category: 'dessert',
label: '',
price: '2.99',
featured: false,
description: 'A delectable, semi-sweet New York Style Cheese Cake, with Graham cracker crust and spiced with Indian cardamoms',
comments: [
{
rating: 5,
comment: "Imagine all the eatables, living in conFusion!",
author: "John Lemon",
date: "2012-10-16T17:57:28.556094Z"
},
{
rating: 4,
comment: "Sends anyone to heaven, I wish I could get my mother-in-law to eat it!",
author: "Paul McVites",
date: "2014-09-05T17:57:28.556094Z"
},
{
rating: 3,
comment: "Eat it, just eat it!",
author: "Michael Jaikishan",
date: "2015-02-13T17:57:28.556094Z"
},
{
rating: 4,
comment: "Ultimate, Reaching for the stars!",
author: "Ringo Starry",
date: "2013-12-02T17:57:28.556094Z"
},
{
rating: 2,
comment: "It's your birthday, we're gonna party!",
author: "25 Cent",
date: "2011-12-02T17:57:28.556094Z"
}
]
}
];
【问题讨论】：
-
你读过
.filter文档，你知道过滤器返回什么吗？ -
filter() 是做什么的？返回一个数组？
var x = [1,2,3]; y = x[0]在处理数组时做了什么？ -
代码应该使用 find() 而不是 filter()
标签： javascript function methods filter syntax