Devesh Tulshyan @code4fun_devesh

Full Stack MERN Web Developer. Technical Writer, Learn New Concepts Everyday, Love What You Do, Post What You Learned. Open for Remote Work. #hireme react-portfolio-devesh.web.app Kolkata, India Joined June 2022

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Devesh Tulshyan @code4fun_devesh

2 years ago

JavaScript #74 Parameters:- function show(text) { alert(text); } show("hello"); // it will alert 'hello'. Function parameters are used to pass values to a function for working with it. This way a function becomes reusable and can render different outputs based on inputs.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #73 Functions :- function show() { alert("hello"); } show(); // it will alert 'hello'. Local Variables are variables declared within a function are not visible outside the function. But, function can access a variable declared outside it called Outer Variables.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #72 Function Declaration :- function message(p1, p2, ....) { // body } First comes the 'function' keyword, then comes the name of the function and parenthesis. Parenthesis include the parameters separated by comma. The function body is between two curly braces.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #71 Functions :- Functions makes programs clean and modular. Functions are used to create a piece of code which does some specific task, and can be re-used anywhere within the program. alert(msg); is also a function, open and closed parenthesis denotes a function.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #70 Switch Statement :- If we pass a value of different type in case, that case will be dead, other lines will get executed until break. Example :- case '0': case '1': case 2: 2 is not a string but a number and if switch was of string type, case 2 will be dead.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #69 Switch Statement :- The value of the switch variable is compared with every value of the cases one by one. The one case which matches gets executed till a break occurs. Also if any values don't match, the default case gets executed. Default case is optional.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #68 Switch Statement :- It is a replacement for multiple if checking statements. Syntax :- switch(x) { case 'value1': // if (x === 'value1') ..... [break] case 'value2': // if (x === 'value2') ..... [break] default: ..... [break] }

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #67 Labels :- outer: for (let i = 0; i < 3; i++) { for (let j = 0; j < 3; j++) { alert(i+j); if(i === 2) break outer; } } If it was normal break, it would have exited out of inner loop, not the outer loop. Same can be used with continue.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #66 The continue directive :- The continue directive is used to skip the loop for some specific conditions. for(let i = 0; i < 5; i++) { if(i % 2 == 0) { continue; } alert(i); } So, when i is even, continue is executed, and alert is skipped.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #65 The break directive :- A loop terminates when it's condition part becomes false, but we can also terminate the loop by force exiting at any time using break directive. for(let i = 0; i < 5; i++) { alert(i); if(i === 3) { break; // exits. } }

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #64 Parts of For Loop can be skipped too. let i = 0; for( ; i < 3; i++) alert(i); 0 1 2 will be the output but we skipped the initial part of the for loop and it is perfectly valid. Also we can skip the increment part, for( ; i < 3; ) alert(i++); 0 1 2

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #63 For Loop :- For alerting 1, 2 and 3 we can use a for loop :- for(let i = 1; i <= 3; i++) { alert(i); } Loop will stop when i becomes 4. The variable i is declared inside of the loop so it is only available inside the loop. It is called inline variable.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #62 For Loop :- It is a more compact loop :- for(begin; condition; step) { statements; } Begin: Executes once in the beginning. Condition: Checks if true at every iteration before entering the loop body. Step: Executes after execution of body in each iteration.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #61 Do-While Loop :- The condition check is done after the loop body is executed. do { statements; } while (condition); This loop will at least execute once because the condition is checked at the end, even if condition is false.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #60 let i = 1; while (i <= 3) { alert(i); i++; } We have i=1, so in the while condition, 1 <= 3 so we get inside the loop. We alert 1, i++ means i becomes 2. Again at the while loop, 2 <= 3 so i gets inside and repeats until i = 3 and then quits.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #59 Basic Loops :- Loops are used to repeat or loop over some statements over and over again. while loop :- while (condition) { loop body, statements here! } This loop repeats till the condition is true, exits the loop when condition becomes false.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #58 Logical Operators :- Nullish coalescing :- It is very similar to OR (||) but, ?? considers only null and undefined to be a false value, whereas OR considers any zero value to be false like "", 0, etc. let marks = 0; marks || 100 gives 100. marks ?? 100 gives 0.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #57 Logical Operators :- Nullish coalescing :- a ?? b returns a if a is defined or b, if a is undefined. let myAge = 20; alert(myAge ?? "Unknown"); Since myAge is defined, it will return 20. let myAge = null; alert(myAge ?? "Unknown"); It will return Unknown.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #56 Logical Operators :- Nullish coalescing :- It treats null and undefined the same way, and other values grouped as another way which may be referred to as defined values. It returns the first argument if defined, otherwise the second undefined argument.

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Devesh Tulshyan @code4fun_devesh

3 years ago

JavaScript #55 Logical Operators :- NOT Working :- It is represented by ! symbol. !true = false, !false = true. Converts to Boolean and reverses the result. !5 = !(true) = false, !0 = !(false) = true. Sometimes, !! is used to convert to Boolean. !!5 = !false = true.