What is the usage of flat in es6

In es6, the flat() method is used to recursively traverse the array according to a specifiable depth, and merge all elements with the elements of the traversed sub-array into a new array and return it, that is, the array is lowered Dimension, the syntax is "Array.prototype.flat()".

The operating environment of this tutorial: Windows 10 system, ECMAScript version 6.0, Dell G3 computer.

What is the usage of flat in es6

Array.prototype.flat()

The flat() method will recursively traverse the array according to a specifiable depth and merge all elements with the elements in the traversed sub-array into A new array is returned.

This is what we call array dimensionality reduction.

Function: Flatten the array and loop through the value of each item. If the value of the item is also an array, take it out (equivalent to removing the [] brackets of the array)

flat(n）

Flatten the array of each item, n defaults to 1, indicating the flattening depth.

To make a long story short, it is to perform a parenthesis removal operation on the Array according to the parameters in flat, and the default is to go to one level .

The following is a simple implementation

```
Array.prototype.myFlat = function (num = 1) {
      if (num < 1) {
        return this
      }
      const res = []
      for (let i = 0; i < this.length; i++) {
        if (Array.isArray(this[i])) {
          res.push(...this[i].myFlat(num - 1))
        } else {
          res.push(this[i])
        }
      }
      return res
    }
```

The idea is relatively simple. If it is a non-array, push it directly. If it is a number, it needs to be processed with a layer of brackets. If you want to remove brackets N times, just call the myFlat method N times.

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