如何将项目添加到待办事项列表

Question

This is a short cut of my addItem function in my todo app, i don't really understand what slice does in this value: this.state.newItem.slice() . Can anybody explain me? Thank you so much!

constructor(props) {
    super(props);
    this.state = {
      newItem: "",
      list: []
    };

addItem() {
    // create a new item with unique id
    const newItem = {
      id: 1 + Math.random(),
  

    **value: this.state.newItem.slice()**

 
    };

    // copy current list of items
    const list = [...this.state.list];

    // add the new item to the list
    list.push(newItem);

    // update state with new list, reset the new item input
    this.setState({
      list,
      newItem: ""
    });
  }

Answer 1

Since the slice returns new string, the slice might have used to copy the string in the above code. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice

Answer 2

First of all why are you use slice method? If you used it to trim your value. you use The trim() method removes whitespace from both sides of a string. The trim() method does not change the original string. Syntax. string.trim().