interviw questions day 2 js

Author: nilajcoder

JavaScript Interview/Day 2/async.js

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+
+/*
+Asynchronous functions allow JavaScript to handle time-consuming tasks efficiently without blocking 
+the execution of other code.
+Common techniques include using callbacks, Promises, and async/await for handling asynchronous operations.
+*/
+
+
+console.log("1"-1);//0
+
+setTimeout(function() {console.log(10)}, 10);//10
+
+console.log(2);//2
+
+setTimeout(function() {console.log(12)}, 10);//12
+setTimeout(function() {console.log(11)}, 9);//11
+
+// 0 2 11 10 12

JavaScript Interview/Day 2/demo.js

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+console.log('1'+1)//11
+/*
+The + operator is used for string concatenation when one of the operands is a string.
+*/
+console.log("1"+1)//11
+
+console.log(1 +"1")//11
+console.log(1-"1")//0
+
+
+/*
+The - operator is used for subtraction, and it does not concatenate strings.
+When using - with a string and a number, JavaScript tries to convert the string to a number.
+
+loosely coupling
+
+*/
+console.log("1"-1)//0
+
+//addition arihematic 
+console.log(1+1)//2
+
+/*
+
+When using the * operator with a string and a number, 
+JavaScript tries to convert the string to a number before performing the multiplication.
+*/
+console.log("3"*2)//
+
+/*
+The / operator is used for division, and it behaves similarly to the 
+* operator in that it also converts the string to a number before performing the division.
+
+
+*/
+console.log("3"/2)// 1.5
+console.log("6"/2)//3
+

JavaScript Interview/Day 2/demo1.js

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+
+/*
+The first console.log subtracts 1 from the string "1", which JavaScript implicitly converts to the number 1, resulting in 0.
+
+The setTimeout function schedules the execution of a function that logs 10 to the console after a 10-millisecond delay.
+
+The final console.log outputs 2 immediately.
+*/
+console.log("1"-1);
+
+setTimeout(function() {console.log(10)}, 10);
+
+console.log(2);// 0 2 10

JavaScript Interview/Day 2/filter.js

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+const arr = [1, 2, 3, 4, 5, 6];
+const greaterThanThree = arr.filter(item => item > 3);
+
+console.log(greaterThanThree);  // Output: [4, 5, 6]

JavaScript Interview/Day 2/find.js

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+
+
+// find method is use to find a specific value from arraay
+
+const arr = [1, 2, 3, 4, 5];
+const found = arr.find(element => element > 3);
+
+console.log(found);  // Output: 4

JavaScript Interview/Day 2/map.js

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+const arr = [1, 2, 3, 4, 5];
+const newArr = arr.map(item => item > 2); // Just returns true or false based on the condition
+
+console.log(newArr);//[ false, false, true, true, true ]

JavaScript Interview/Day 2/reduce.js

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+const arr = [1, 2, 3, 4, 5];
+const newArr = arr.reduce((acc ,curr)=> acc*curr);
+
+console.log(newArr);//120

JavaScript Interview/Day 2/var.js

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+/*
+let var & const
+-----------------
+var: variable can be redeclared & updated. A global scope variable  before 2015 we used var
+
+
+but in 2015 in javascript has new features called ES6 and we use the following keyword
+
+let:variable can not be re-declared but can be updated. block scope variable.
+
+const: variable can not be re-declared or updated.A block scope variable.
+
+*/
+
+
+// line by line execution
+
+//a = 10;
+console.log(a);//undefined
+var a;
+a=10
+//let a;  This code will throw a ReferenceError because you're trying to assign a value to a before it's initialized due to the temporal dead zone.