JavaScript Introduction: We can Write JavaScript code in places of HTML document We can Write JavaScript code in places of HTML document Body Location: Execute Script when web page is loading. <html> <body> <script> alert(“Alert box while loading page”); </script> </body></html> Head Location: Execute Script on action (for example click on button). <html> <head> <script> …
Comments: Comments are used to describe the code or document. These are 2 types Single line Comment: It is represented by double forward slashes (//). <!doctype html><html> <body> <script> var a=10; var b=20; var c=a+b; // + operator add values of a & b and store result into c document.write(c); // write() – display information …
Variable: Syntax: Example: var identity; orlet identity; var name = “amar”;var age = 23;var salary = 35000.00; Rules to create variable: Variable Declaration, Assignment, Modify and Initialization: Declaration: A variable without value is called declaration var a; let b; Assignment: Assigning value to variable which is already declared. var a; // declarationa = 10; // assignment …
Function: Syntax: Example: function identity() { ….. Logic ….. } function add() { var a=10, b=20; var c = a+b; print(c); } Note: We always perform operations when action performed. For example, display alert message when user clicks on button <html> <head> <script> function clickMe() { alert(“Hello”); } </script> </head> <body> <h2> JavaScript …
Classifications: Depends on taking input parameters and return values, functions classified into four types. No Parameters &No Return values With Parameters &No Return values With Parameters &With Return values No Parameters &With Return values function say(){ write(“Hello”);} function add(a, b){ var c = a+b; write(c);} function add(a, b){ var c = a+b; return c;} function …
Call By Value: <html> <body> <p id=”demo”></p> <script> function modify(y) { y=y+10; document.write(“y inside function : ” + y); } var x = 10 ; modify(x); document.getElementById(“demo”).innerHTML = x; </script> </body></html> Call By Reference: <html> <body> <p id=”demo”></p> <script> function modify(x) { x[0]=x[0]+10; document.write(“x[0] inside function : ” + x[0]); } var arr = [10, …
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Explain Higher Order Functions in JavaScript: Functions that operate on other functions, either by taking them as arguments or by returning them, are called higher-order functions. Function takes function as argument: <html> <body> <script> function abc() { document.write(“Hello world”) } function higherOrder(xyz) { xyz(); } higherOrder(abc); </script> </body></html> Function returning function: <html> <body> <script> function …
Local variables: <html> <head> <script> function add(){ var a=10; var b=20; var c=a+b; document.write(“Sum is : ” + c); } </script> </head> <body> <button onclick=”add()”>add</button> </body></html> Global variables: Defining variables outside to all functions – we can them from all functions. <html> <head> <script> var a=5; var b=3; function add(){ document.write(“Sum is : ” + …
Var Let Const Variable can be either Global Scope or Local Scope Variable is Local scope Variable is Local Scope Re-Declaration or Updating of variable is possible Only Updating possible Nothing is possible. Hoisting allowed – Variables initializes with “undefined” Hoisting allowed – Variables not initializes with values. Hoisting allowed – Variables not initializes with …
Format Output: The table giving the examples to concatenate the messages with values: Syntax Example int + int -> int 10 + 20 = 30 String + String -> String “Hello” + “World” -> HelloWorld “10” + “20” -> 1020 String + int -> String “Sum = “ + 10 -> Sum = 10 String …