fileNameChange

• 1st - file name change

      'use strict';
        
      const fs = require('fs'),
          path = require('path');
        
        
      const arr = fs.readdirSync('./src/html/');
      let arr2 = [];
      let obj;
      let arr4;
      let obj2 = {};
        
      arr.map(file => path.join('./src/html/', file))
          .filter(file => fs.statSync(file).isFile())
          .forEach(file => {
              const extname = path.extname(file);
              const basename = path.basename(file);
              if (extname === '.html') {
                  arr2.push(String(basename));
              }
          })
        
      obj = arr2.reduce((a, x) => {
          if (!a[x[0]]) a[x[0]] = [];
          a[x[0]].push(x);
          return a;
      }, {})
        
      arr4 = Object.keys(obj).map(function (key) {
          return obj[key];
      });
        
        
      for (let i=0; i<arr4.length; i++) {
          let n = i < 10? '0'+i : i;
          let m = 0;
          for (let j=0; j<arr4[i].length; j++) {
              m = j < 10? '0' + j : j;
              obj2[arr4[i][j]] = n + '_' + m + '_' + arr4[i][j];
          }
      }
        
        
      for (const property in obj2) {
          let oldPath = path.join('./src/html/', property);
          let newPath = path.join('./src/html/', obj2[property]);
          fs.rename(oldPath, newPath, (err) => {
              if (err) throw err;
              console.log('Rename complete!');
          })
      }