immutability helper functions for javascript

react-immutability-helper.js

// Immutable specfic object in the array
   
   onUpdateItem(index, e) {
      const options = [...this.state.options];
      const newObject = {
        ...options[index],
        [fieldName]: event.target.value
      };
      options.splice(index, 1, newObject);
      this.setState({ options });
   }

  // Mutable array example
  onUpdateItem2(index, e) {
        const groups = [...this.state.groups];
        groups[index].name = e.target.value;
        this.setState({ groups });
     }
  }

  onAddItem() {
    const newRow = {
      id: uniqueId('option-')
    };
    const rows = [...this.state.rows, newRow];
    this.setState({rows});
  }

  onDeleteItem(deleteIdx) {
    const rows = this.state.rows.filter((item, idx) => idx !== deleteIdx);
    this.setState({rows});
  }

  onDeleteItem2(deleteIdx) {
    let {rows} = this.state;
    rows = [
      ...rows.slice(0,deleteIdx),
      ...rows.slice(deleteIdx+1),
    ];
    this.setState({rows});
  }