无法在本机反应中打印在 this.state.arr 中声明的数组？

Question

I have an array called this.state.arr , which I added values to in another function in my app.js file. In the render() function I console.log(this.state.arr) the array to show and it shows like this:

[]
  0: "a"
  1: "b"
  2: "c"
  length: 3

However, I want to be able to access the individual elements of each array. I've tried this.state.arr[0], or const list = this.state.arr.map((e) => {return e;}); I've also tried some other commands to access the insides of the this.state.arr array.

But none of those worked. I just kept getting null in the console when I tried to access the inner elements of the array. Any help would be greatly appreciated!

Answer 1

Having null get returned for your attempts to access items in this.state.arr is pretty unusual and makes me think that something else is populating or interfering with your array. When you try to access an item at an index your array that doesn't have a value undefined will get returned. null is typically used to indicate a value/property/attribute is intentionally being set to blank. I'd double check where you are setting / accessing the arr. Posting that part of the code may help.