es10 and output ques updated

Author: lgope

ES10-or-ECMAScript2019/basicOfES10.js

@@ -5,16 +5,16 @@ console.log(array.flat(2)); // [ 1, 2, 3, [ 4 ], [ 5 ] ]
 
 // #2 Turning this array into a new array: [ 'Hello young grasshopper!', 'you are', 'learning fast!' ]
 const greeting = [
-  ['Hello', 'young', 'grasshopper!'],
-  ['you', 'are'],
-  ['learning', 'fast!']
+  ["Hello", "young", "grasshopper!"],
+  ["you", "are"],
+  ["learning", "fast!"],
 ];
 
-console.log(greeting.flatMap(x => x.join(' '))); // [ 'Hello young grasshopper!', 'you are', 'learning fast!' ]
+console.log(greeting.flatMap((x) => x.join(" "))); // [ 'Hello young grasshopper!', 'you are', 'learning fast!' ]
 
 //#3 Turning the greeting array above into a string: 'Hello young grasshopper you are learning fast!'
 
-console.log(greeting.flatMap(x => x.join(' ')).join(' ')); // Hello young grasshopper! you are learning fast!
+console.log(greeting.flatMap((x) => x.join(" ")).join(" ")); // Hello young grasshopper! you are learning fast!
 
 //#4 Turning the trapped 3 number into: [3]
 const trapped = [[[[[[[[[[[[[[[[[[[[[[[[[[3]]]]]]]]]]]]]]]]]]]]]]]]]];
@@ -23,7 +23,7 @@ console.log(trapped.flat(Infinity)); // [ 3 ]
 // Infintiy is actually a LARGE number in JavaScipt. It represents the maximum amount of memory that we can hold for a number! For more here: https://riptutorial.com/javascript/example/2337/infinity-and--infinity
 
 //#5 Cleaning up this email to have no whitespaces. Make the answer be in a single line (return a new string):
-const userEmail3 = '     cannotfillemailformcorrectly@gmail.com   ';
+const userEmail3 = "     cannotfillemailformcorrectly@gmail.com   ";
 
 console.log(userEmail3.trimEnd().trimStart()); // cannotfillemailformcorrectly@gmail.com
 
@@ -34,9 +34,72 @@ const usersArray = Object.entries(users);
 
 //#7 changing the output array of the above to have the user's IDs multiplied by 2 -- Should output:[ [ 'user1', 36546 ], [ 'user2', 185666 ], [ 'user3', 180630 ] ]
 
-updatedUsersArray = usersArray.map(user => [user[0], user[1] * 2]);
+updatedUsersArray = usersArray.map((user) => [user[0], user[1] * 2]);
 
 //#8 changing the output array of  #7 back into an object with all the users IDs updated to their new version. Should output: { user1: 36546, user2: 185666, user3: 180630 }
 
 const updatedUsers = Object.fromEntries(updatedUsersArray);
 console.log(updatedUsers); // { user1: 36546, user2: 185666, user3: 180630 }
+
+// Array.flat() && Array.flatMap
+const jobs = [
+  ["👮🏻", "💂🏻"],
+  ["👷🏻‍♂️", "🤴🏻"],
+];
+const flatJobs = jobs.flat(); // same as: const flatJobs = jobs.flat(1);
+
+console.log(flatJobs); // ['👮🏻', '💂🏻', '👷🏻‍♂️', '🤴🏻']
+
+const jobsList = [
+  ["👮🏻", "💂🏻"],
+  ["👷🏻‍♂️", "🤴🏻", ["🎅🏻", ["🦸🏻"], "🦹🏻‍♀️"]],
+];
+const flatJobsList = jobsList.flat(Infinity); // Infinity: flatten an array of arbitrary depth
+
+console.log(flatJobsList); // ['👮🏻', '💂🏻', '👷🏻‍♂️', '🤴🏻', '🎅🏻', '🦸🏻', '🦹🏻‍♀️']
+
+const names = ["police", "guard", "builder", "princess"];
+
+const mappedOnly = flatJobs.map((job, index) => [job, names[index]]);
+const mappedAndFlatten = flatJobs.flatMap((job, index) => [job, names[index]]);
+
+console.log(mappedOnly); // [['👮🏻', 'police'], ['💂🏻', 'guard'], ['👷🏻‍♂️', 'builder'], ['🤴🏻', 'princess']]
+console.log(mappedAndFlatten); //  ['👮🏻', 'police', '💂🏻', 'guard', '👷🏻‍♂️', 'builder', '🤴🏻', 'princess']
+
+// From Entries
+const fruits = { lemon: "🍋", pineapple: "🍍", mango: "🥭", apple: "🍏" };
+const entries = Object.entries(fruits);
+
+console.log(Object.entries(fruits)); // [['lemon', '🍋'],['pineapple', '🍍'],['mango', '🥭'],['apple', '🍏']]
+console.log(Object.fromEntries(entries)); // {lemon: '🍋', pineapple: '🍍', mango: '🥭', apple: '🍏'}
+
+// String.trimStart() & String.trimEnd()
+const fruitsList = "    🥭🍏🍍     ";
+console.log(fruitsList.trimEnd()); // "    🥭🍏🍍";
+console.log(fruitsList.trimStart()); // "🥭🍏🍍     ";
+
+// Stable Array.prototype.sort()
+const fruitsArr = [
+  { name: "🥝", units: 12 },
+  { name: "🫐", units: 14 },
+  { name: "🍏", units: 16 },
+  { name: "🥬", units: 15 },
+  { name: "🍊", units: 18 },
+  { name: "🍐", units: 19 },
+];
+
+// Create our own sort criteria function:
+const sortCriteria = (fruit1, fruit2) => fruit1.units - fruit2.units;
+
+// Perform stable ES10 sort:
+const sorted = fruitsArr.sort(sortCriteria);
+
+console.log(sorted);
+// [
+//   { name: "🥝", units: 12 },
+//   { name: "🫐", units: 14 },
+//   { name: "🥬", units: 15 },
+//   { name: "🍏", units: 16 },
+//   { name: "🍊", units: 18 },
+//   { name: "🍐", units: 19 },
+// ];