在数组上查找对象的索引

Question

我想搜索一个对象数组来查找特定id的索引。让我们看看：

下面是我的对象的数组：

var sentences = [0,
{ id: "1-1", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined },
{ id: "1-2", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined },
{ id: "1-3", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined },
{ id: "2-1", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined },
{ id: "2-2", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined },
{ id: "2-3", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined },
];

例如，我希望找到id: "2-1"的索引，即4。我怎么能这么做？

我试过这样的方法但没有成功.

pos = sentences.map(function(e) { return e.sentences.id; }).indexOf('2-1');
console.log(pos)

Answer 1

这里最好的方法是使用findIndex()

​

var sentences = [0, { id: "1-1", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined }, { id: "1-2", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined }, { id: "1-3", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined }, { id: "2-1", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined }, { id: "2-2", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined }, { id: "2-3", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined }, ];
const res = sentences.findIndex(x => x.id === "2-1");
console.log(res)

​

您的方法中的问题是，您正在从e.sentences.id返回map()，这将导致错误。你只需要返回e.id

pos = sentences.map(function(e) { return e.id; }).indexOf('2-1');

利用箭头函数

pos = sentences.map(e => e.id).indexOf('2-1');

Answer 2

您可以接受Array#findIndex并检查该值是否为特鲁西，以防止不能具有属性的null。

​

var sentences = [0, { id: "1-1", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined }, { id: "1-2", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined }, { id: "1-3", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined }, { id: "2-1", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined }, { id: "2-2", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined }, { id: "2-3", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined }],
    index = sentences.findIndex(o => o &&  o.id === '2-1');

console.log(index);

​

Answer 3

此代码将帮助您找到对象和索引。

var sentences = [0,
{ id: "1-1", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined },
{ id: "1-2", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined },
{ id: "1-3", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined },
{ id: "2-1", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined },
{ id: "2-2", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined },
{ id: "2-3", layer: ["A1", "A2", "A3", "A4", "A5"], difficulty: 4, track: "end", start: 4, end: 6, accuracy: undefined , accent: undefined, meaning_weight: undefined, shadow_weight: undefined, write_weight: undefined },
];

let res = sentences.find((each) => { return each.id == "2-1"});
let index = sentences.indexOf(res);
console.log(res, index);