From de01bf878ba8f3066e0098a77d7640e1b86c3ede Mon Sep 17 00:00:00 2001
From: vaishnavme <42497931+vaishnavme@users.noreply.github.com>
Date: Sun, 19 Dec 2021 14:21:29 +0530
Subject: [PATCH] Polyfill for forEach, map, filter, reduce, bind and
 promise.all

---
 Snippets/Polyfill/bind-polyfill.js       | 10 ++++++++++
 Snippets/Polyfill/filter-polyfill.js     | 12 ++++++++++++
 Snippets/Polyfill/forEach-polyfill.js    |  7 +++++++
 Snippets/Polyfill/map-polyfill.js        | 10 ++++++++++
 Snippets/Polyfill/promiseAll-polyfill.js | 21 +++++++++++++++++++++
 Snippets/Polyfill/reduce-polyfill.js     | 14 ++++++++++++++
 6 files changed, 74 insertions(+)
 create mode 100644 Snippets/Polyfill/bind-polyfill.js
 create mode 100644 Snippets/Polyfill/filter-polyfill.js
 create mode 100644 Snippets/Polyfill/forEach-polyfill.js
 create mode 100644 Snippets/Polyfill/map-polyfill.js
 create mode 100644 Snippets/Polyfill/promiseAll-polyfill.js
 create mode 100644 Snippets/Polyfill/reduce-polyfill.js

diff --git a/Snippets/Polyfill/bind-polyfill.js b/Snippets/Polyfill/bind-polyfill.js
new file mode 100644
index 0000000..c3d6e7b
--- /dev/null
+++ b/Snippets/Polyfill/bind-polyfill.js
@@ -0,0 +1,10 @@
+// bind polyfill
+
+Function.prototype.customBind = function (...args) {
+   let context = this;
+   let params = args.slice(1);
+
+   return function (...args2) {
+      context.apply(args[0], [...params, ...args2]);
+   };
+};
diff --git a/Snippets/Polyfill/filter-polyfill.js b/Snippets/Polyfill/filter-polyfill.js
new file mode 100644
index 0000000..80fd40c
--- /dev/null
+++ b/Snippets/Polyfill/filter-polyfill.js
@@ -0,0 +1,12 @@
+// filter polyfill
+
+Array.prototype.customFilter = function (callbackFn) {
+   const result = [];
+
+   for (let i = 0; i < this.length; i++) {
+      if (callbackFn.call(this, this[i], i)) {
+         result.push(this[i]);
+      }
+   }
+   return result;
+};
diff --git a/Snippets/Polyfill/forEach-polyfill.js b/Snippets/Polyfill/forEach-polyfill.js
new file mode 100644
index 0000000..faeaa84
--- /dev/null
+++ b/Snippets/Polyfill/forEach-polyfill.js
@@ -0,0 +1,7 @@
+// forEach polyfill
+
+Array.prototype.customForEach = function (callbackFn) {
+   for (let i = 0; i < this.length; i++) {
+      callbackFn.call(this, this[i], i);
+   }
+};
diff --git a/Snippets/Polyfill/map-polyfill.js b/Snippets/Polyfill/map-polyfill.js
new file mode 100644
index 0000000..27326cf
--- /dev/null
+++ b/Snippets/Polyfill/map-polyfill.js
@@ -0,0 +1,10 @@
+// map polyfill
+
+Array.prototype.customMap = function (callbackFn) {
+   const result = [];
+
+   for (let i = 0; i < this.length; i++) {
+      result.push(callbackFn.call(this, this[i], i));
+   }
+   return result;
+};
diff --git a/Snippets/Polyfill/promiseAll-polyfill.js b/Snippets/Polyfill/promiseAll-polyfill.js
new file mode 100644
index 0000000..9a53798
--- /dev/null
+++ b/Snippets/Polyfill/promiseAll-polyfill.js
@@ -0,0 +1,21 @@
+// promise polyfill
+
+Promise.customAll = function (promiseArray) {
+   return new Promise((resolve, reject) => {
+      let completed = 0;
+      const promiseResults = [];
+
+      promiseArray.forEach((value, index) => {
+         Promise.resolve(value)
+            .then((result) => {
+               completed++;
+               promiseResults[index] = result;
+
+               if (completed === promiseArray.length) {
+                  resolve(promiseResults);
+               }
+            })
+            .catch((err) => reject(err));
+      });
+   });
+};
diff --git a/Snippets/Polyfill/reduce-polyfill.js b/Snippets/Polyfill/reduce-polyfill.js
new file mode 100644
index 0000000..9a31b2e
--- /dev/null
+++ b/Snippets/Polyfill/reduce-polyfill.js
@@ -0,0 +1,14 @@
+// reduce polyfill
+
+Array.prototype.customReduce = function (callbackFn, initialValue) {
+   let accumulator = initialValue;
+
+   for (let i = 0; i < this.length; i++) {
+      if (accumulator !== undefined) {
+         accumulator = callbackFn.call(undefined, accumulator, this[i], i, this);
+      } else {
+         accumulator = this[i];
+      }
+   }
+   return accumulator;
+};