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250 lines (184 loc) 路 4.55 KB
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/**
* QUESTION 01
* OUTPUT
*/
let obj = {
a: 10,
b: 20,
};
let obj2 = {
a: 10,
b: 20,
};
console.log(obj == obj2);
console.log(obj === obj2);
let obj3 = obj;
console.log(obj3 == obj);
console.log(obj3 === obj);
/**
* QUESTION 02
* OUTPUT
*/
var arr = [1, 2, 3, 4, 5];
for (var i = 0; i < arr.length; i++) {
setTimeout(() => console.log(arr[i]), 500);
}
const arr1 = [1, 2, 3, 4, 5];
for (let i = 0; i < arr1.length; i++) {
setTimeout(() => console.log(arr1[i]), 500);
}
/**
* QUESTION 03
* OUTPUT
*/
console.log(1);
setTimeout(() => console.log(2), 0);
console.log(3);
Promise.resolve(console.log(4));
/**
* QUESTION 04
* How to compare two arrays
*/
let a1 = [1, 2, 3];
let a2 = [1, 2, 3];
console.log(a1 == a2);
console.log(JSON.stringify(a1) == JSON.stringify(a2));
/**
* QUESTION 05
* Calculate total point (using reduce) and avg result
*/
let EXAM = [
{
Subeject: "English",
result: {
point: 80,
grade: "A+",
},
},
{
Subeject: "Physics",
result: {
point: 85,
grade: "A+",
},
},
{
Subeject: "Math",
result: {
point: 89,
grade: "A+",
},
},
];
let totalRes = 0;
EXAM.map((subject) => (totalRes += subject.result.point));
console.log(totalRes);
console.log((totalRes / EXAM.length).toFixed(2));
let res = EXAM.reduce(
(accumulator, currentValue) => accumulator + currentValue.result.point,
0
);
console.log(res);
/**
* QUESTION 06
*
* Merge two objects in one object
*/
let obj1 = {
a: 10,
b: 20,
};
let obj2 = {
c: 30,
d: 20,
};
obj1 = { ...obj1, ...obj2 };
console.log(obj1);
// more test
const a = [1, 2, 5, 7, 9];
const b = [2, 5, 7, 12, 100];
// const c = [...a, ...b];
const c = a.concat(b).sort((a, b) => a > b);
console.log(c);
const obj = {
x: 1,
getX() {
const inner = function () {
console.log(this.x);
};
inner.bind(this)();
},
};
obj.getX();
const arrayTotal = a.reduce((t, i) => t + i);
console.log(arrayTotal);
// OUTPUT
const arr = [1, 2, 3, 4, 5];
arr.push(arr.push(arr.push(arr.pop())));
console.log(arr);
// OUTPUT
const arrayOfOddNumbers = [1, 3, 5];
arrayOfOddNumbers[100] = 199;
console.log(arrayOfOddNumbers.length);
// OUTPUT
class MyClass extends (String, Array) {
construct() {}
}
const a = new MyClass();
console.log(a instanceof Array); // true
// OUTPUT
["1101100000111110", "1101110100011111"]
.map((s) => String.fromCharCode(parseInt(s, 2)))
.reduce((acc, n) => acc + n, "");
// Preserve immutability of objects
const heroes = [
{ name: "Wolverine", family: "Marvel" },
{ name: "Batman", family: "DC Comics" },
];
const newHeroes = heroes.map((hero) => (hero.name = hero.name.toUpperCase()));
console.log(heroes);
// Right way
const newHeroes2 = heroes.map((hero) =>
Object.assign({}, hero, { name: hero.name.toUpperCase() })
); // or return {...h, name: h.name.toUpperCase()};
console.log(heroes);
// What is the problem with sort() function? Why javascript introduced toSorted() function
/**
* Ans: sort() function mutates the original array
* toSorted() method takes an array and returns a new array with the elements sorted in ascending order. It does not mutate the original array. All undefined elements are sorted to the end of the array.
* */
const arr = [1, 8, 6, 9, 7, 100, 400, 200];
const oldSortedArr = arr.sort((a, b) => a - b);
console.log(arr); // [1, 6, 7, 8, 9, 100, 200, 400] (mutated the original array)
console.log(oldSortedArr, arr); // [1, 6, 7, 8, 9, 100, 200, 400]
const newSortedArr = arr.toSorted((a, b) => a - b);
console.log(arr); // [1, 6, 7, 8, 9, 100, 200, 400] (does not mutated the original array)
console.log(newSortedArr); // [1, 6, 7, 8, 9, 100, 200, 400]
// Remove the duplicates item from an array without build in funcitons
const arr = [4, 1, 8, 5, 2, 1, 8, 4, 7, 5, 6, 9];
const removeDuplicates = (arrData) => {
const obj = {};
for (const item of arrData) {
obj[item] = item;
}
return Object.values(obj);
};
console.log(removeDuplicates(arr));
// Write a program for array intersection (keep the only common items from two arrays) (without build in functions)
const arr = [1, 4, 5, 6, 9];
const arr1 = [2, 1, 7, 5, 9, 6];
const getCommonItems = (arrData, arrData1) => {
const obj = {};
const resArr = [];
for (const item of arrData) {
obj[item] = item;
}
for (const item1 of arrData1) {
if (obj[item1]) resArr.push(item1);
}
return resArr;
};
console.log(getCommonItems(arr, arr1));
// Optional => using build in functions
const intersectedArr = arr.filter((item) => arr1.includes(item));
console.log(intersectedArr);