React - 按降序对对象进行排序，在更改时重新渲染 DOM

Question

I have a react app I'm working on, where I need to update the DOM again after a change has been made - sorting numbers from highest to lowest based on word count in a paragraph.

So far this looks like this:

import "./styles.css";
// this represents a couple of paragraphs where we count the words
import text from "./text.js";

export default function App() {
  let allTheWords = text.split(" ");
  let countData = [];
  let theWordCount = {};
  const createTable = () => {
    for (const num of allTheWords) {
      theWordCount[num] = theWordCount[num] ? theWordCount[num] + 1 : 1;
    }
    for (const property in theWordCount) {
      countData.push(
        <tr key={property}>
          <td>{property}</td>
          <td>{theWordCount[property]}</td>
        </tr>
      );
    }
  };
  createTable();
  // let's sort the words, but we need to go from high to small
  const sortWords = () => {
    theWordCount = Object.entries(theWordCount)
      .sort(([, a], [, b]) => a - b)
      .reduce((r, [k, v]) => ({ ...r, [k]: v }), {});
    console.log("OKAY I THINK WE SORTED: " + JSON.stringify(theWordCount));
    createTable();
  };
  return (
    <div>
      <button onClick={sortWords}>SORT WORDS</button>
      <table>
        <tbody>
          <tr>
            <th>Word</th>
            <th>Count</th>
          </tr>
          {countData}
        </tbody>
      </table>
    </div>
  );
}

The output of this block is this:

OKAY I THINK WE SORTED: {"10":1,"27":1,"1815":1,"1842":1,"1852":1,"Augusta":1,"King,":1,"(née":1,"Byron;":1,"December":1,"–":1,"November":1,"1852)":1,"English":1,"writer,":1,"chiefly":1,"proposed":1,"mechanical":1,"general-purpose":1,"computer,":1,"recognise":1,"machine":1,"had":1,"applications":1,"pure":1,"calculation,":1,"have":1,"published":1,"intended":1,"As":1,"result,":1,"regarded":1,"programmer.[2][3][4]\n\nAda":1,"child":1,"poet":1,"Lord":1,"Lady":1,"Byron.[5]":1,"All":1,"Byron's":1,"children":1,"were":1,"wedlock":1,"women.[6]":1,"separated":1,"his":1,"wife":1,"month":1,"after":1,"left":1,"England":1,"forever":1,"four":1,"months":1,"later.":1,"commemorated":1,"parting":1,"poem":1,"begins,":1,"\"Is":1,"face":1,"like":1,"mother's":1,"fair":1,"child!":1,"ADA!":1,"sole":1,"daughter":1,"house":1,"heart?\".[7]":1,"Greece":1,"when":1,"eight":1,"old.":1,"mother":1,"bitter":1,"promoted":1,"Ada's":1,"interest":1,"mathematics":1,"logic":1,"effort":1,"prevent":1,"developing":1,"father's":1,"perceived":1,"insanity.":1,"Despite":1,"this,":1,"him,":1,"naming":1,"two":1,"sons":1,"Gordon.":1,"Upon":1,"death,":1,"buried":1,"next":1,"request.":1,"Although":1,"ill":1,"childhood,":1,"pursued":1,"studies":1,"assiduously.":1,"married":1,"William":1,"1835.":1,"made":1,"Earl":1,"1838,":1,"thereby":1,"becoming":1,"Lovelace.\n\nHer":1,"educational":1,"social":1,"exploits":1,"brought":1,"into":1,"contact":1,"scientists":1,"Andrew":1,"Crosse,":1,"Sir":1,"David":1,"Brewster,":1,"Wheatstone,":1,"Michael":1,"Faraday":1,"author":1,"Dickens,":1,"contacts":1,"which":1,"used":1,"further":1,"education.":1,"described":1,"approach":1,"science\"[8]":1,"herself":1,"\"Analyst":1,"(&":1,"Metaphysician)\".[9]\n\nWhen":1,"teenager":1,"(18),":1,"mathematical":1,"talents":1,"long":1,"working":1,"relationship":1,"friendship":1,"fellow":1,"British":1,"who":1,"\"the":1,"father":1,"computers\".":1,"particular":1,"met":1,"June":1,"1833,":1,"through":1,"their":1,"mutual":1,"friend,":1,"private":1,"tutor,":1,"Mary":1,"Somerville.\n\nBetween":1,"1843,":1,"translated":1,"article":1,"Italian":1,"military":1,"engineer":1,"Luigi":1,"Menabrea":1,"engine,":1,"supplementing":1,"it":1,"elaborate":1,"set":1,"notes,":1,"simply":1,"called":1,"\"Notes\".":1,"Lovelace's":1,"are":1,"important":1,"early":1,"history":1,"computers,":1,"containing":1,"what":1,"consider":1,"program—that":1,"is,":1,"designed":1,"Other":1,"historians":1,"reject":1,"this":1,"perspective":1,"point":1,"personal":1,"1836/1837":1,"contain":1,"programs":1,"engine.[10]":1,"also":1,"developed":1,"vision":1,"capability":1,"computers":1,"go":1,"mere":1,"or":1,"number-crunching,":1,"while":1,"others,":1,"including":1,"Babbage":1,"himself,":1,"focused":1,"those":1,"capabilities.[11]":1,"mindset":1,"science\"":1,"ask":1,"questions":1,"Engine":1,"(as":1,"shown":1,"notes)":1,"examining":1,"how":1,"individuals":1,"society":1,"relate":1,"technology":1,"collaborative":1,"tool.[6]\n\nShe":1,"uterine":1,"cancer":1,"age":1,"36.":1,"Countess":2,"known":2,"for":2,"work":2,"Engine.":2,"beyond":2,"algorithm":2,"carried":2,"such":2,"machine.":2,"is":2,"often":2,"computer":2,"only":2,"other":2,"born":2,"He":2,"thy":2,"my":2,"died":2,"years":2,"Her":2,"remained":2,"interested":2,"him":2,"at":2,"King":2,"Babbage,":2,"\"poetical":2,"led":2,"about":2,"calculating":2,"notes":2,"many":2,"Lovelace":3,"mathematician":3,"on":3,"Babbage's":3,"Analytical":3,"that":3,"be":3,"by":3,"from":3,"with":3,"She":4,"out":4,"she":4,"Byron":4,"Charles":5,"an":6,"first":6,"as":6,"Ada":8,"was":9,"a":9,"to":13,"in":14,"of":15,"and":16,"her":16,"the":18}

So now what we need to do, is sort this from highest number to lowest number.

Sorting object property by values

In ES8, you can use Object.entries() to convert the object into an array:

const maxSpeed = { car: 300, bike: 60, motorbike: 200, airplane: 1000, helicopter: 400, rocket: 8 * 60 * 60 };

const sortable = Object.entries(maxSpeed) .sort(([,a],[,b]) => ab) .reduce((r, [k, v]) => ({ ...r, [k]: v }), {});

console.log(sortable);

We're running with this answer successfully with this:

    const sortWords = () => {
        theWordCount = Object.entries(theWordCount)
          .sort(([, a], [, b]) => a - b)
          .reduce((r, [k, v]) => ({ ...r, [k]: v }), {});
        console.log("OKAY I THINK WE SORTED: " + JSON.stringify(theWordCount));
        createTable();
      };

So now, we need to change this so the large numbers come first on our way down to the small numbers

https://www.w3schools.com/jsref/jsref_sort.asp

Example Sort numbers in an array in descending order:

const points = [40, 100, 1, 5, 25, 10]; points.sort(function(a, b){return ba});

https://www.codegrepper.com/code-examples/javascript/array+sort+from+higher+to+lower+in+js

“array sort from higher to lower in js” Code Answer's

sorting array from highest to lowest javascriptjavascript by Arqa
on Mar 25 2020 Comment 14 1 // Sort an array of numbers 2 let numbers = [5, 13, 1, 44, 32, 15, 500] 3 ​ 4 // Lowest to highest 5 let lowestToHighest = numbers.sort((a, b) => a - b); 6 //Output: [1,5,13,15,32,44,500] 7 ​ 8 //Highest to lowest 9 let highestToLowest = numbers.sort((a, b) => ba); 10 //Output: [500,44,32,15,13,5,1]

So I try:

    const sortWords = () => {
        theWordCount = Object.entries(theWordCount)
          .sort(([, a], [, b]) => b - a)
          .reduce((r, [k, v]) => ({ ...r, [k]: v }), {});
        console.log("OKAY I THINK WE SORTED: " + JSON.stringify(theWordCount));
        createTable();
      };

But it doesn't sort high to low, it does this:

OKAY I THINK WE SORTED: {"10":1,"27":1,"1815":1,"1842":1,"1852":1,"the":18,"and":16,"her":16,"of":15,"in":14,"to":13,"was":9,"a":9,"Ada":8,"an":6,"first":6,"as":6,"Charles":5,"She":4,"out":4,"she":4,"Byron":4,"Lovelace":3,"mathematician":3,"on":3,"Babbage's":3,"Analytical":3,"that":3,"be":3,"by":3,"from":3,"with":3,"Countess":2,"known":2,"for":2,"work":2,"Engine.":2,"beyond":2,"algorithm":2,"carried":2,"such":2,"machine.":2,"is":2,"often":2,"computer":2,"only":2,"other":2,"born":2,"He":2,"thy":2,"my":2,"died":2,"years":2,"Her":2,"remained":2,"interested":2,"him":2,"at":2,"King":2,"Babbage,":2,"\"poetical":2,"led":2,"about":2,"calculating":2,"notes":2,"many":2,"Augusta":1,"King,":1,"(née":1,"Byron;":1,"December":1,"–":1,"November":1,"1852)":1,"English":1,"writer,":1,"chiefly":1,"proposed":1,"mechanical":1,"general-purpose":1,"computer,":1,"recognise":1,"machine":1,"had":1,"applications":1,"pure":1,"calculation,":1,"have":1,"published":1,"intended":1,"As":1,"result,":1,"regarded":1,"programmer.[2][3][4]\n\nAda":1,"child":1,"poet":1,"Lord":1,"Lady":1,"Byron.[5]":1,"All":1,"Byron's":1,"children":1,"were":1,"wedlock":1,"women.[6]":1,"separated":1,"his":1,"wife":1,"month":1,"after":1,"left":1,"England":1,"forever":1,"four":1,"months":1,"later.":1,"commemorated":1,"parting":1,"poem":1,"begins,":1,"\"Is":1,"face":1,"like":1,"mother's":1,"fair":1,"child!":1,"ADA!":1,"sole":1,"daughter":1,"house":1,"heart?\".[7]":1,"Greece":1,"when":1,"eight":1,"old.":1,"mother":1,"bitter":1,"promoted":1,"Ada's":1,"interest":1,"mathematics":1,"logic":1,"effort":1,"prevent":1,"developing":1,"father's":1,"perceived":1,"insanity.":1,"Despite":1,"this,":1,"him,":1,"naming":1,"two":1,"sons":1,"Gordon.":1,"Upon":1,"death,":1,"buried":1,"next":1,"request.":1,"Although":1,"ill":1,"childhood,":1,"pursued":1,"studies":1,"assiduously.":1,"married":1,"William":1,"1835.":1,"made":1,"Earl":1,"1838,":1,"thereby":1,"becoming":1,"Lovelace.\n\nHer":1,"educational":1,"social":1,"exploits":1,"brought":1,"into":1,"contact":1,"scientists":1,"Andrew":1,"Crosse,":1,"Sir":1,"David":1,"Brewster,":1,"Wheatstone,":1,"Michael":1,"Faraday":1,"author":1,"Dickens,":1,"contacts":1,"which":1,"used":1,"further":1,"education.":1,"described":1,"approach":1,"science\"[8]":1,"herself":1,"\"Analyst":1,"(&":1,"Metaphysician)\".[9]\n\nWhen":1,"teenager":1,"(18),":1,"mathematical":1,"talents":1,"long":1,"working":1,"relationship":1,"friendship":1,"fellow":1,"British":1,"who":1,"\"the":1,"father":1,"computers\".":1,"particular":1,"met":1,"June":1,"1833,":1,"through":1,"their":1,"mutual":1,"friend,":1,"private":1,"tutor,":1,"Mary":1,"Somerville.\n\nBetween":1,"1843,":1,"translated":1,"article":1,"Italian":1,"military":1,"engineer":1,"Luigi":1,"Menabrea":1,"engine,":1,"supplementing":1,"it":1,"elaborate":1,"set":1,"notes,":1,"simply":1,"called":1,"\"Notes\".":1,"Lovelace's":1,"are":1,"important":1,"early":1,"history":1,"computers,":1,"containing":1,"what":1,"consider":1,"program—that":1,"is,":1,"designed":1,"Other":1,"historians":1,"reject":1,"this":1,"perspective":1,"point":1,"personal":1,"1836/1837":1,"contain":1,"programs":1,"engine.[10]":1,"also":1,"developed":1,"vision":1,"capability":1,"computers":1,"go":1,"mere":1,"or":1,"number-crunching,":1,"while":1,"others,":1,"including":1,"Babbage":1,"himself,":1,"focused":1,"those":1,"capabilities.[11]":1,"mindset":1,"science\"":1,"ask":1,"questions":1,"Engine":1,"(as":1,"shown":1,"notes)":1,"examining":1,"how":1,"individuals":1,"society":1,"relate":1,"technology":1,"collaborative":1,"tool.[6]\n\nShe":1,"uterine":1,"cancer":1,"age":1,"36.":1} 

How do you sort an object in this fashion from high to low?

I tried

.sort(([, b], [, a]) => b - a)

.sort(([b, ], [a, ]) => b - a)

.sort(([, a], [, b]) => b - a)

None of it worked, how do I do what's done in Sorting object property by values but backwards?

In the sortWords function, I call; createTable(); but the DOM doesn't update, because render is only called once.

I need to update it somehow, do I call render again somehow?

Answer 1

The problem is not in the sorting function, that works fine. You can see that the order is broken for object properties that consist only of numbers. You can see it in this simple example:

const t = {a: 1, b: 2, c: 3};
console.log('Order of keys is preserved', t);

const s = {a: 1, b: 2, "10": 3};
console.log('Order of keys is ruined', s);

I am not sure what exactly you can do about it... Some thoughts:

1. Do not bother with sorting object keys, instead use another more suitable data structure.

2. If you absolutely need to use object with sorted keys, you could append space to the key when doing the reduce , and then using trim whenever you need to use the key (very stupid idea, but it would work for preserving the key order):

const u = {" a": 1, " b": 2, " 10": 3};
console.log('Ordering of keys preserved', u);