Just Code (Shhh) | Tipify (DamengRandom)

# Just Code (Shhh)

1. If changes one of object values inside same array, we need to use spread operator (...) or JSON.parse(JSON.stringify()) way to trigger the state changes and get component re-rendered !!!! Code example:

// sort array of objects !!
function compareVotes( a, b ) {
  if ( a.upvotes < b.upvotes ) return 1;
  if ( a.upvotes > b.upvotes ) return -1;
  return 0;
}

// Way 1:
const afterSorted = JSON.parse(JSON.stringify(articles.sort(compareVotes)));

// Way 2:
const afterSorted = [...articles.sort(compareVotes)];

// Then we can set the changed value:
setCurrent(afterSorted);

Completed version below:

import React, { useState } from 'react';
import Articles from './Articles';

function compareDate( a, b ) {
  if ( a.date < b.date ) return 1;
  if ( a.date > b.date ) return -1;
  return 0;
}

function compareVotes( a, b ) {
  if ( a.upvotes < b.upvotes ) return 1;
  if ( a.upvotes > b.upvotes ) return -1;
  return 0;
}

let articles = [
  {
    title: 'abc test',
    upvotes: 53,
    date: '2019-11-12'
  },
  {
    title: 'cde omg, what?',
    upvotes: 23,
    date: '2020-1-12'
  },
  {
    title: 'test me test now ...',
    upvotes: 33,
    date: '2021-9-12'
  }
];


export default function ArticleWrapper() {
  const [current, setCurrent] = useState(articles);

  const sortByVotes = () => {
    // const afterSorted = JSON.parse(JSON.stringify(articles.sort(compareVotes)));
    const afterSorted = [...articles.sort(compareVotes)];
    setCurrent(afterSorted);
    console.log("votes", current);
  };
  
  const sortByDate = () => {
    // const afterSorted = JSON.parse(JSON.stringify(articles.sort(compareDate)));
    const afterSorted = [...articles.sort(compareDate)];
    setCurrent(afterSorted);

    console.log("dates", current);
  };

  return (
    <div>
      <h3>Re-render the list after using sort !!!</h3>
      <div>
        <button onClick={sortByVotes}>sort by upvotes</button>
        <button onClick={sortByDate}>sort by date</button>
      </div>
      <Articles articles={current} />
      {/* Articles component is used for returning tables of articles */}
    </div>
  )
}

Reference: here

2. How to save data like object format instead of array format in NodeJS

app.post('/posts', async (req, res) => {
  const id = randomBytes(4).toString('hex'); // will generate a random hash id value
  const { title } = req.body;

  posts[id] = {
    id,
    title,
  };

  // event bus (emit event !!!!)
  await axios.post('http://localhost:9225/events', {
    type: 'PostCreated',
    data: {
      id,
      title,
    }
  });

  res.status(201).send(posts[id]);
});

3. KnexJS insert data for existing records specific column

// One example of using knex for seeding existing records specific column data

/**
 * Complete SETUP Guidance (V1.0)
 *
 * STEP 1: setup dbName value: either CLIENT_TABLE_NAME or AUDIT_CLIENT_TABLE_NAME
 * Code for client table -> const dbName = dbTableName.CLIENT_TABLE_NAME;
 * Code for audit_client table -> const dbName = dbTableName.AUDIT_CLIENT_TABLE_NAME;
 *
 * STEP 2: setup mode either mock/test data injection or real data injection
 * Code for mock/test injection -> const simulationEnabled = true;
 * Code for real injection -> const simulationEnabled = false;
 *
 * STEP 3: setup clientId either id or audit_id
 * Code for client table -> const clientId = client.id;
 * Code for audit_client table -> const clientId = client.audit_id;
 *
 * STEP 4: setup condition query id either id or audit_id
 * Code for client table -> .where("id", clientId)
 * Code for audit_client table -> .where("audit_id", clientId)
*/

"use strict";

require("dotenv").config();
const dbTableName = require("../lib/const/dbTableName");
const knexCustom = require("../lib/knexCustom");
const { uuid } = require('uuidv4');

// records batch
const itemsPerBatch = 100;
// need to use the table name which needs to generate existing cs_client_id (configurable)
// const dbName = dbTableName.CLIENT_TABLE_NAME;
const dbName = dbTableName.AUDIT_CLIENT_TABLE_NAME;
// Set this to 'true' to get the 'Total affected record' without actually affecting the records
// const simulationEnabled = true;
const simulationEnabled = false;

async function updateClientCsClientId(extractAllCsClientIds, client) {
  let csClientIdObject = {};

  if (!client.cs_client_id
    || (client.cs_client_id && 10 !== client.cs_client_id.length)
  ) {
    while (true) {
      client.cs_client_id = uuid();
      csClientIdObject = {
        csClientId: client.cs_client_id,
        isNew: true,
      };

      if (!extractAllCsClientIds.includes(client.cs_client_id)) {
        break;
      }
    }
  } else {
    csClientIdObject = {
      csClientId: client.cs_client_id,
      isNew: false,
    };
  }

  return csClientIdObject;
}

async function main() {
  console.log("process.env.APP_ENV", process.env.APP_ENV);

  let sqlResponseCount;
  const extractAllCsClientIds = [];

  sqlResponseCount = await knexCustom(dbName)
  .count("*")
  .catch((err) => {
    console.error(err);
  });

  const recordCount = sqlResponseCount[0].count;
  const batchCount = Math.ceil(recordCount * 1.0 / itemsPerBatch);
  let errorRecordCount = 0;
  let affectedRecordCount = 0;
  let skippedRecordCount = 0;

  for (let i = 0; i < batchCount; i++) {
    console.log(`Processing batch sequence ${i}...`);

    sqlResponseCount = await knexCustom(dbName)
    .orderBy("id", "asc")
    .limit(itemsPerBatch)
    .offset(i * itemsPerBatch)
    .catch((err) => {
      console.error(err);
    });

    for (let j = 0; j < sqlResponseCount.length; j++) {
      const client = sqlResponseCount[j];
      // const theId = client.id;
      const theId = client.audit_id;
      const { csClientId, isNew } = await updateClientCsClientId(extractAllCsClientIds, client);
      extractAllCsClientIds.push(csClientId);

      if (isNew) {
        console.log(`Updating cs client id: ${csClientId} for id: ${theId} ...`);

        if (simulationEnabled) {
          affectedRecordCount++;
        } else {
          let errorFound = false;

          await knexCustom(dbName)
          .update({
            cs_client_id: csClientId,
          })
          // .where("id", theId)
          .where("audit_id", theId)
          .catch((err) => {
            errorFound = true;
            console.error(err);
          });

          if (errorFound) {
            errorRecordCount++;
          } else {
            affectedRecordCount++;
          }
        }
      } else {
        console.log(`Unmodified client ${theId} skipped.`);

        skippedRecordCount++;
      }
    }
  }

  await knexCustom.destroy();
  console.log(`simulationEnabled: ${simulationEnabled}`);
  console.log(`Total error record    : ${errorRecordCount}`);
  console.log(`Total affected record : ${affectedRecordCount}`);
  console.log(`Total skipped record  : ${skippedRecordCount}`);
  console.log(`Total record          : ${recordCount}`);
  console.log("Updating updateClientCsClientId done!");
}

main()
.catch((err) => {
  console.error(err);
});

4. Palindrome interview question demo:

function palindrome(word) {
  if (typeof word === 'string') {
		var regex = /[^A-Za-z]/g;
  
 	 	word = word.toLowerCase().replace(regex, '');
  
  	var wordLength = word.length;
  
  	for (let i = 0; i < wordLength/2; i++) {
			if (word[i] !== word[wordLength-1-i]) {
				return false;
			}
 
			return true;
		}
  } else {
  	console.log('Input must be a string ..');
  }
}

console.log(palindrome('kyayk')); // true
console.log(palindrome('damon')); // false

5. Find the same elements which occurred in 2 arrays

// 2 List of strings and return same elements which occurred in both array lists

// const arr1 = ['1', '2', '4'];
// const arr2 = ['11', '43', '55', '2', '832', '66', '4', '222', '1212'];
const arr1 = ['I', 'love', 'Ella', '!'];
const arr2 = ['Come', 'on', 'Ella', ',', 'you', 'can', 'make', 'it', '!'];

const commonElements = arr1.filter(el => arr2.includes(el));

console.log(commonElements);

// if using underscore js or lodash js, we can use a function called `intersection`
// eg: 
_.intersection(arr1, arr2);

6. Merge 2 arrays and remove repeated elements

const arr2 = ['I', 'love', 'Ella', '!'];
const arr1 = ['Come', 'on', 'Ella', ',', 'you', 'can', 'make', 'it', '!'];

const merged = [...arr1, ...arr2];
const mergedWithoutRepeats = [...new Set(merged)]; // remove repeat elements inside array

console.log(mergedWithoutRepeats);