在二维数组 Javascript 中查找零索引数据

Question

获取二维数组中所有0索引数据javascript

let a = [["", "2", "", ""], ["1", "3", "", ""], ["", "", "4", ""]]
index = 0

output = ["", "1", ""]

同样获取所有剩余的索引数据

index= 1
output = ["2", "3", ""]

Answer 1

获取第一个索引：

const result = Array.map(a=>a[0]);

result 将包含嵌套数组中所有元素的第一个索引。这通过遍历数组并获取第一个索引元素来工作

Answer 2

您可以使用reduce

遍历arr 并为arr 中的每个元素循环遍历以获取所需的索引值并将其推送到op。

let a = [["", "2", "", ""], ["1", "3", "", ""], ["", "", "4", ""]]

function getIndex(arr,index){
  return arr.reduce((op,inp) => {
    let val = inp.find((e,i) => i === index )
    op.push(val)
    return op
  },[])
}

console.log(getIndex(a,0))
console.log(getIndex(a,1))

Answer 3

您可以使用 Array#map method with ES6 destructuring feature。解构有助于从对象中提取某些属性（Javascript数组也是对象）。

let a = [
  ["", "2", "", ""],
  ["1", "3", "", ""],
  ["", "", "4", ""]
];
let index = 0;

let output = a.map(({[ index ]: v }) => v)

console.log(output);


index = 1;

output = a.map(({[ index ]: v }) => v)

console.log(output);

Answer 4

使用 lodash，您可以将索引用作迭代器：

const result = _.map(a, 1);

在二维数组 Javascript 中查找零索引数据

Find zero index data in 2d Array Javascript

javascript

multidimensional-array

underscore.js

ecmascript-6

lodash