JavaScript Basics
In this video we will discuss <br />1. Is JavaScript case sensitive <br />2. Comments in JavaScript <br />3. Data types in JavaScript <br /> <br />Is JavaScript case sensitive <br />Yes, JavaScript is case sensitive programming language. Variable names, keywords, methods, object properties and event handlers all are case sensitive. <br /> <br />Example 1 : alert() function name should be all small letters <br /> <br /> alert("JavaScripts Basics Tutorial"); <br /> <br /> <br />Example 2 : Alert() is not same as alert(). Throws Alert is not defined error. To see the error press F12 key. <br /> <br /> Alert("JavaScripts Basics Tutorial"); <br /> <br /> <br />Comments in JavaScript : There are 2 types of comments in JavaScript. <br />1) Single Line Comment <br /> <br />Example : <br /> <br /> // This is a sinle line comment <br /> <br /> <br />2) Multi Line Comment <br /> <br />Example: <br /> <br /> /* This is a <br /> multi line <br /> comment */ <br /> <br /> <br />Data types in JavaScript <br /> <br />The following are the different data types in JavaScript <br />Numbers - 5, 5.234 <br />Boolean - true / false <br />String - "MyString", 'MyString' <br /> <br />To create a variable in JavaScript use var keyword. Variable names are case sensitive. <br /> <br />In c# to create an integer variable we use int keyword <br />int X = 10; <br /> <br />to create a string variable we use string keyword <br />string str = "Hello" <br /> <br />With JavaScript we always use var keyword to create any type of variable. Based on the value assigned the type of the variable is inferred. <br />var a = 10; <br />var b = "MyString"; <br /> <br />In C#, you cannot assign a string value to an integer variable <br />int X = 10; <br />X = "Hello"; // Compiler error <br /> <br />JavaScript is a dynamically typed language. This means JavaScript data types are converted automatically as needed during script execution. Notice that, in myVariable we are first storing a number and then a string later. <br /> <br /> var myVariable = 100; <br /> alert(myVariable); <br /> myVariable = "Assigning a string value"; <br /> alert(myVariable); <br /> <br /> <br />When a + operator is used with 2 numbers, JavaScripts adds those numbers. <br /> <br /> var a = 10; <br /> var b = 20; <br /> var c = a + b; <br /> alert(c); <br /> <br /> <br />Output : 30 <br /> <br />When a + operator is used with 2 strings, JavaScript concatenates those 2 strings <br /> <br /> var a = "Hello " <br /> var b = "JavaScript"; <br /> var c = a + b; <br /> alert(c); <br /> <br /> <br />Output : Hello JavaScript <br /> <br />When a + operator is used with a string and a number, JavaScript converts the numeric value to a string and performs concatenation. <br /> <br /> var a = "Number is : " <br /> var b = 10; <br /> var c = a + b; <br /> alert(c); <br /> <br /> <br />Output : Number is 10 <br /> <br /> <br /> var a = "50" <br /> var b = 10; <br /> var c = a + b; <br /> alert(c); <br /> <br /> <br />Output : 5010 <br /> <br />But if you use a minus operator, numeric value is not converted to string <br /> <br /> var a = "50" <br /> var b = 10; <br /> var c = a - b; <br /> alert(c); <br /> <br /> <br />Output : 40