polyfill for Function.prototype.bind()

swarajlaha · May 29, 2021 · f8d8bf9 · f8d8bf9
1 parent 6552b26
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diff --git a/Day 2/bind.js b/Day 2/bind.js
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+/**
+ * Polyfill - Function.prototype.bind()
+ * The bind() method creates a new function that, when called, has its this keyword set to the provided value, with a given sequence of arguments preceding any provided when the new function is called.
+ * The below user defined function is a polyfill for the .bind() function, which is predefined in the prototype of Function object.
+ * myBind() - Returns a function.
+ */
+
+let name = {
+  firstName: "Swaraj",
+  lastName: "Laha"
+};
+
+let printName = function(job, location, country) {
+  console.log(this.firstName + " " + this.lastName, "works as an " + job + " in " + location + ", " + country);
+};
+
+// Function.prototype.bind()
+let printMyName = printName.bind(name, "Analyst");
+printMyName("Hyderabad", "India");  // O/p: 'Swaraj Laha works as an Analyst in Hyderabad, India'
+
+// Ployfill
+Function.prototype.myBind = function(...args) {
+  let value = this;
+  let params = args.slice(1); // Returns all elements of array - args, except the 1st element
+  return function (...argsPloyfill) {
+    value.apply(args[0], [...params, ...argsPloyfill]);
+  }
+};
+
+// Function.prototype.myBind()
+let printMyNamePolyfill = printName.myBind(name, "Analyst");
+printMyNamePolyfill("Hyderabad", "India");  // O/p: 'Swaraj Laha works as an Analyst in Hyderabad, India'
diff --git a/index.html b/index.html
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+<!DOCTYPE html>
+<html>
+  <head>
+    <style></style>
+    <script src="./Day 2/bind.js"></script>
+  </head>
+  <body></body>
+</html>