feat: added group by question & formatting

currying/infiniteCurrying.js

@@ -23,10 +23,10 @@
 // };
 
 function infiniteCurryingWithVariableArg(func) {
-  function recursiveCurry(...args){
+  function recursiveCurry(...args) {
     return function(...a) {
-      if(!a.length){
-        return args.reduce((result, value)=>{
+      if (!a.length) {
+        return args.reduce((result, value) => {
           return func.call(func, result, value);
         });
       }
@@ -37,10 +37,10 @@ function infiniteCurryingWithVariableArg(func) {
 };
 
 function infiniteCurrying(func) {
-  function recursiveCurry(...args){
+  function recursiveCurry(...args) {
     return function(a) {
-      if(!a){
-        return args.reduce((result, value)=>{
+      if (!a) {
+        return args.reduce((result, value) => {
           return func.call(func, result, value);
         });
       }
@@ -50,6 +50,7 @@ function infiniteCurrying(func) {
   return recursiveCurry();
 };
 
+// Arrow Functions
 const fn = infiniteCurrying((a, b) => a + b);
 const fn2 = infiniteCurryingWithVariableArg((a, b) => a + b);
 console.log(fn(7)(8)(9)());

js-coding-questions/groupBy.js

@@ -0,0 +1,44 @@
+// Suppose you have input like:
+
+var skillsArray = [
+  { skill: 'css', user: 'Bill' },
+  { skill: 'javascript', user: 'Chad' },
+  { skill: 'javascript', user: 'Bill' },
+  { skill: 'css', user: 'Sue' },
+  { skill: 'javascript', user: 'Sue' },
+  { skill: 'html', user: 'Sue' }
+];
+
+// Convert it into result of the following form:
+// [
+//   { skill: 'javascript', user: [ 'Chad', 'Bill', 'Sue' ], count: 3 },
+//   { skill: 'css', user: [ 'Sue', 'Bill' ], count: 2 },
+//   { skill: 'html', user: [ 'Sue' ], count: 1 } 
+// ]
+
+function groupBySkill(array) {
+  return Object.values(array.reduce((result, { skill, user }) => {
+    if (!result[skill]) {
+      return { ...result, [skill]: { skill, user: [user], count: 1 } };
+    }
+    const obj = result[skill];
+    return { ...result, [skill]: { skill, user: obj.user.concat(user), count: obj.count + 1 } }
+  }, {})).sort((a, b) => a.count < b.count ? 1 : -1);
+}
+
+console.log(groupBySkill(skillsArray));
+
+
+// function groupBySkill(array) {
+//   return array.reduce((result, { skill, user }) => {
+
+//     const skillExists = result.filter((res) => res.skill === skill).length;
+
+//     if (!result.length || !skillExists) {
+//       return result.concat({ skill, user: [user], count: 1 })
+//     }
+//     return result.map((res) => {
+//       return skill === res.skill ? { ...res, user: res.user.concat(user), count: res.count + 1 } : res;
+//     })
+//   }, []).sort((a, b) => a.count < b.count ? 1 : -1)
+// }