Question

我是React的新手，我想在单击Modal的Ok时推送值。例如，如果我要添加鸡蛋滴，然后添加鸡肉卷饼，那么这两个都将以导航栏状态Total_Item添加到数组中。

问题是添加了项，但是数组的长度保持为2。似乎数组大小保持不变，并且一个数组保存在另一个数组中。我需要确定长度大小，以便以后可以运行逻辑以保持唯一值。请查看菜单组件并检查Listval（）函数。

我需要更正推送数组逻辑。请参阅沙箱： https://codesandbox.io/s/mutable-water-8779d

谢谢

应用组件


import React, {Component} from "react";
import Navbar from "./components/Navbar";
import "./styles.css";

class App extends Component {
render (){
  return (
    <div className="App">
      <h1>Hello CodeSandbox</h1>
      <h2>Start editing to see some magic happen!</h2>
      <Navbar/>
    </div>
  );


}
   
}

export default App;

导航栏组件

import React, {Component} from "react";
import Menu from "./Menu";

class Navbar extends Component {
  state={
Category:[
  {
    id:1,
    FoodType: "Chinese",
    Menu:["Egg Drop", "Chicken Fried", "Beef Fried"],
    Price:[2,8,10]
    },
    
    {
      id:2,
      FoodType: "Mexican",
      Menu:["Veg Burrito", "Chicken Burrito", "Beef Burrito"],
      Price:[7,8,10]
      }

],

One_Item:[
{
  listvalue:null,
  Select_Item:null,
  Select_Price:null,
  Select_Quantity:null,
  Select_Item_TotalPrice:null

}

],

Cart_Item:[

  {
Total_Item:[]

  }
]



  };




  render() {
    return (

   <Menu
  //  len={this.state.length}
  //  FoodTypes_list = {this.state.map(e => e.FoodType)}
  //  MenuList_list={this.state.map(e => e.Menu)}


Objs_Type={this.state.Category}




  //  FoodTypes={this.state.Type1.FoodType}
  //  MenuList={this.state.Type1.Menu}
 
   />

    );


  }
}
export default Navbar;

菜单组件

import React, { Component } from "react";
import { Modal } from "react-bootstrap";
import NumericInput from "react-numeric-input";

class Menu extends Component {
  state = {
    addModalShow: false,
    copied: false
  };

  ModalShow = () => {
    this.setState({ addModalShow: true });
  };

  async ModalText(e) {
    await this.setState({ listvalue: e.target.innerHTML });

    //  console.log(this.state.listvalue);
  }

  ModalClose = () => {
    this.setState({ addModalShow: false });
  };

  async Listval() {
    let ll = "$" + this.state.listvalue.replace(/[^0-9]/g, "");

    let ll2 = this.state.listvalue.replace(/\d+/g, "");
    let ll3 = ll2.replace(/\$/g, "");

    let ll4 = ll.replace(/\$/g, "");
    let ll5 = this.state.Select_Quantity;
    let ll6 = parseFloat(ll4) * ll5;

    let ll7 = [this.state.Total_Item];
    ll7.push(ll3);

    // this.state.ll7.map((e,idx) => {
    //   key={idx}
    // };

    // for(var i=0;i<ll7.length;i++){
    //   // push the component to elements!
    //  return ll7[key=i]
    // };

    // ll7.filter((item,index)=>{
    //   return ll7.indexOf(item)===index
    // });

    // let ll2='$'+ll.replace(/[^0-9]/g,'');
    await this.setState({ Select_Price: ll });
    await this.setState({ Select_Item: ll3 });
    await this.setState({ Select_Item_TotalPrice: ll6 });

    await this.setState({ Total_Item: ll7 });

    console.log(this.state.Total_Item);
  }

  stylesList = {
    display: "inline-block",
    background: "#C8C8C8",
    width: "500px",
    height: "50px"
  };

  onhover = e => {
    e.target.style.background = "red";
  };

  offhover = e => {
    e.target.style.background = "#C8C8C8 ";
  };

  render() {
    return <div className="container-fluid">{this.Mapping_Type()}</div>;
  }

  Mapping_Type() {
    let result_type = this.props.Objs_Type.map(a => a.FoodType);
    let result_menu = this.props.Objs_Type.map(a => a.Menu);
    let result_price = this.props.Objs_Type.map(a => a.Price);

    let newFoodtype = [];
    let newMenu = [];
    let FoodType_Menu = [];
    let Price_new = [];
    for (let i = 0; i < result_type.length; i++) {
      let temp1 = <h1> Menu {result_type[i]}</h1>;
      let temp2 = result_menu[i].map((item, idx) => (
        <div style={this.stylesList}>
          <ul style={{ padding: 0 }}>
            {/* <CopyToClipboard> */}
            <li
              id={idx}
              style={{ listStyleType: "none" }}
              key={item.id}
              className={"listitems"}
              onMouseOver={this.onhover}
              onMouseOut={this.offhover}
              onClick={e => {
                this.ModalShow();
                this.ModalText(e);
              }}
            >
              {" "}
              {item} {result_price[i][idx]}{" "}
            </li>
            {/* </CopyToClipboard> */}

            <Modal
              style={{ opacity: 1 }}
              size="md"
              aria-labelledby="contained-modal-title-vcenter"
              show={this.state.addModalShow}
              onHide={this.ModalClose}
            >
              <Modal.Header closeButton>
                <Modal.Title id="contained-modal-title-vcenter">
                  Large Modal
                </Modal.Title>
              </Modal.Header>
              <Modal.Body>
                <div className="container">
                  {this.state.listvalue}
                  <br />
                  <NumericInput
                    min={1}
                    max={1000}
                    value={this.state.Select_Quantity}
                    onChange={value =>
                      this.setState({ Select_Quantity: value })
                    }
                    style={{ float: "right", width: "500px", padding: "10px" }}
                  />

                  <br />

                  <button
                    class="btn btn-primary btn-sm pull-right"
                    onClick={() => {
                      this.Listval();
                    }}
                  >
                    OK
                  </button>
                </div>
              </Modal.Body>
            </Modal>
          </ul>
        </div>
      ));

      FoodType_Menu.push(temp1, temp2);
    }
    return FoodType_Menu;
  }
}

export default Menu;

Answer 1

Total_Item?本身不是数组吗？

执行此操作时：

let ll7 = [this.state.Total_Item];

您正在创建一个包含[]数组的数组（Total_Item）。然后，用这一行：

ll7.push(ll3);

您将ll3推入数组。因此，您的数组现在包含Total_Item数组和ll3。

如果Total_Item是一个数组，则为：

let ll7 = this.state.Total_Item || []; ll7.push(ll3);

或者，如果您想要一个独立的数组，则可以使用...扩展运算符：

let ll7 = [...(this.state.Total_Item || [])]; ll7.push(ll3);

推送数组的长度保持不变

1 个答案: