Java script
0 likes72 views
1. JavaScript can be used to program the behavior of web pages by changing HTML content and styles, hiding and showing HTML elements, and writing output in different ways. 2. JavaScript uses variables to store and work with data values. Variables are declared with var and assigned values using the equal sign. 3. JavaScript statements are made up of expressions, operators, and variables to perform actions like assigning values, performing calculations, and writing output.
Java script
- 1. B Y G O U R I S H A N K A R R P U J A R JavaScript
- 2. Introduction 1. HTML to define the content of web pages 2. CSS to specify the layout of web pages 3. JavaScript to program the behaviour of web pages
- 3. JavaScript Can Change HTML Content document.getElementById("demo").innerHTML = "Hello JavaScript"; JavaScript Can Change HTML Styles (CSS) document.getElementById("demo").style.fontSize = "35px";
- 4. JavaScript Can Hide HTML Elements document.getElementById("demo").style.display = "none"; JavaScript Can Show HTML Elements document.getElementById("demo").style.display = "block";
- 5. JavaScript Where To ? <script> document.getElementById("demo").innerHTML = "My First JavaScript"; </script> <p id="demo"></p>
- 6. Functions <script> function myFunction() { document.getElementById("demo").innerHTML = "Paragraph changed."; } </script> <h1>A Web Page</h1> <p id="demo">A Paragraph</p> <button type="button" onclick="myFunction()">Try it</button>
- 7. Tips You can Place JavaScript tag inside HTML in any Part like <head> <script> Test Function </script> </head> <body> You can write all your mark-up Here. <script> Test Function </script> </body>
- 8. Tips You can Include all functions in External sheet & call them in respective page. As like We have did in CSS – External Stylesheet Like that we can also have External Script. <script src=“script.js”></script>
- 9. JavaScript Output JavaScript can "display" data in different ways: Writing into an HTML element, using innerHTML. Writing into the HTML output using document.write(). Writing into an alert box, using window.alert(). Writing into the browser console, using console.log().
- 10. document.getElementById("demo").innerHTML = 5 + 6; document.write(5 + 6); <button type="button" onclick="document.write(5 + 6)">Try it</button> window.alert(5 + 6); console.log(5 + 6);
- 11. JavaScript Statements var x, y, z; // Statement 1 x = 5; // Statement 2 y = 6; // Statement 3 z = x + y; // Statement 4 var a, b, c; // Declare 3 variables a = 5; // Assign the value 5 to a b = 6; // Assign the value 6 to b c = a + b; // Assign the sum of a and b to c
- 12. var x, y; // How to declare variables x = 5; y = 6; // How to assign values z = x + y; // How to compute values Fixed values are called literals. Variable values are called variables. Strings are text, written within double or single quotes:
- 13. JavaScript Variables In a programming language, variables are used to store data values. JavaScript uses the var keyword to declare variables. An equal sign is used to assign values to variables. var x; x = 6;
- 14. Operations document.getElementById("demo").innerHTML = "John" + " " + "Doe"; var x, y; x = 5 + 6; y = x * 10; Numbers are not allowed as the first character. This way JavaScript can easily distinguish identifiers from numbers.
- 15. Comments Code after double slashes // or between /* and */ is treated as a comment. var x = 5; // I will be executed // var x = 6; I will NOT be executed
- 16. Tips All JavaScript identifiers are case sensitive. The variables lastName and lastname, are two different variables. JavaScript does not interpret VAR or Var as the keyword var. In JavaScript, the first character must be a letter, or an underscore (_), or a dollar sign ($). Hyphens are not allowed in JavaScript. They are reserved for subtractions.
- 17. Variables var price1 = 5; var price2 = 6; var total = price1 + price2; <p id="demo"></p> <script> var carName = "Volvo"; document.getElementById("demo").innerHTML = carName; </script>
- 18. var person = "John Doe", carName = "Volvo", price = 200; If you put a number in quotes, the rest of the numbers will be treated as strings, and concatenated.