05. How to convert the data of a two-dimensional array (an array inside an array) into a string

1. Data situation:

First, the data obtained from the backend is:let arr = [1,[10,20],[20,30],40]

Second, the target data is:'1,10-20,20-30,40'

2. Operation process:

First, convert the data into:[1, '10-20', '20-30', 40]

A. Code display:

let arr = [1,[10,20],[20,30],40]
let first_res =  arr.map(item => {
    
    
  if(Array.isArray(item)) {
    
      // 此时是为了区分 item 是二维的数组还是非数组的值;
    let res = item.join("-") // 此时是将二维数组中的 ',' 换成 '-' 的操作;
    return res   // 将操作后的二维数组返回;
  } else {
    
    
    return item // 将非数组的值返回;
  }
})
console.log(first_res,565656);   // 此时的输出结果为：[1, '10-20', '20-30', 40]

B. Result display:

Second, convert the data into target data:'1,10-20,20-30,40'

A. Code display:

let first_res = [1, '10-20', '20-30', 40]
let second_res = first_res.map(it => {
    
    
        if(typeof it === "string") {
    
     // 此时是区分：it 是字符串类型和非字符串类型;
          return it   // 字符串类型就直接返回;
        } else {
    
    
          let res = it.toString()  // 非字符串类型就转化成字符串类型再返回;
          return res
        }
      })
      console.log(second_res, 787878787); // 此时的输出结果为：['1', '10-20', '20-30', '40'] (即：字符串类型的数组)
      console.log(second_res.toString(),78978999999); // 此时的输出结果就是目标值：'1,10-20,20-30,40'
      

B. Result display:

3. Summary:

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