added 5 important buil in functions ..

Author: lgope

README.md

@@ -1,2 +1,71 @@
 # JavaScript
-The of this repo is to save my js programs. Basics of JavaScript. Beginner level.
+*JavaScript, often abbreviated as JS, is a programming language that conforms to the ECMAScript specification. JavaScript is high-level, often just-in-time compiled, and multi-paradigm. It has curly-bracket syntax, dynamic typing, prototype-based object-orientation, and first-class functions. The of this repo is to save my js programs. Basics of JavaScript. Beginner level.*
+
+## Table of Contents
+
+  1. [Important Methods](#methods)
+  
+## Methods
+>  Most important javascript build in methods
+
+<a name="typeof"></a><a name="1.1"></a>
+- [1.1](#typeof) **typeof**: Returns the type.
+ 
+ ```javascript
+ console.log(typeof 44); // number
+
+ console.log(typeof 'something'); // string 
+ 
+ console.log(typeof true); // boolean
+ 
+ let num = 12;
+ console.log(typeof(num)); // number
+ 
+ ```
+
+<a name="toString"></a><a name="1.2"></a>
+- [1.2](#toString) **toString**: Returns the string representation of the number's value.
+ 
+ ```javascript
+ let num = 10;
+ let n = num.toString();
+ 
+ console.log(typeof(num)); // number
+ 
+ console.log(typeof(n)); // string
+ ```
+
+<a name="indexOf"></a><a name="1.3"></a>
+- [1.3](#indexOf) **indexOf**: Returns the first index at which a given element can be found in the array, or -1 if it is not present.
+ 
+ ```javascript
+ let str = "Hello world, welcome to the JS Universe.";
+ console.log(str.indexOf("welcome")); // 13
+ console.log(str.indexOf("wall")); // -1
+ 
+ const fruits = ['Orange', 'Pineapple', 'Apple', 'Melon'];
+ console.log(fruits.indexOf('Melon')); // 3
+ 
+ console.log(fruits.indexOf('klkljkh')); // -1
+ ```
+ 
+<a name="lastIndexOf"></a><a name="1.4"></a>
+- [1.4](#lastIndexOf) **lastIndexOf**: Returns the last index at which a given element can be found in the array, or -1 if it is not present.
+ 
+ ```javascript 
+ const fruits = ['Orange', 'Pineapple', 'Apple', 'Melon'];
+ console.log(fruits.lastIndexOf('Melon')); // 3
+ 
+ console.log(fruits.lastIndexOf('klkljkh')); // -1
+ ```
+ 
+ <a name="length"></a><a name="1.5"></a>
+- [1.5](#length) **length**: Returns the number of characters or size in a string or array.
+ 
+ ```javascript 
+ const fruits = ['Orange', 'Pineapple', 'Apple', 'Melon'];
+ console.log(fruits.length); // 4
+ 
+ let str = "Hello world, welcome to the JS Universe.";
+ console.log(str.length); // 40
+ ```