小编fro*_*ops的帖子

我正在使用 Reactstrap 并动态显示我的卡片，无论我尝试什么，它们似乎都想垂直堆叠。这是呈现它们的组件：

import React, { Component } from 'react';
import { Link } from 'react-router-dom';
import { connect } from 'react-redux';
import { CardDeck } from 'reactstrap';
import { fetchMerch } from '../actions/fetchMerchAction';
import { fetchUniqueMerch } from '../actions/fetchUniqueMerchAction';
import ItemCard from './ItemCard';
import shortid from 'shortid';

class ShopHome extends Component {

  componentDidMount() {
    this.props.onInitMerch();
  }

  showItemDetailHandler = (id) => {
    // console.log("*",id);
    this.props.onInitUniqueMerch(id);
    this.props.history.push(`detail/${this.props.id}`)
  }

  render() {

    let cards;
    if ( this.props.cards ) {
      cards = Object.values(this.props.cards).map( card …

在W3 School Array Sort的这个示例中,函数displayCars似乎被调用了2次.它在第一个函数之前和第一个函数内部调用.有人可以解释这背后的原因吗？我无法理解为什么.提前致谢.

var cars = [
{type:"Volvo", year:2016},
{type:"Saab", year:2001},
{type:"BMW", year:2010}]

displayCars();

function myFunction() {
    cars.sort(function(a, b){return a.year - b.year});
    displayCars();
}

function displayCars() {
  document.getElementById("demo").innerHTML =
  cars[0].type + " " + cars[0].year + "<br>" +
  cars[1].type + " " + cars[1].year + "<br>" +
  cars[2].type + " " + cars[2].year;
}

<div id="demo"></div>