JS

cheatsheet
  1. JS variable
    2. const PI = 3.14159;
  2. JS loop
    3. for (let i = 0; i < 5; i++) {
            console.log("Index: " + i);
            }
  3. JS conditional statement
    4. let x = 10;
            if (x > 5) {
            console.log("x is greater than 5");
            } else {
            console.log("x is less than or equal to 5");
            }
  4. JS object
    5. let person = {
            name: "John",
            age: 30,
            city: "New York"
            };
  5. JS array
    6. let numbers = [1, 2, 3, 4, 5];
  6. JS function
    7. function greet(name) {
            console.log("Hello, " + name + "!");
            }
  7. JS array method (push)
    8. let fruits = ["apple", "banana"];
fruits.push("orange");
  8. JS array method (pop)
    9. let fruits = ["apple", "banana", "orange"];
fruits.pop();
  9. JS array method (forEach)
    10. let numbers = [1, 2, 3, 4, 5];
numbers.forEach(function(number) {
console.log(number);
});
  10. JS string method (concat)
    11. let str1 = "Hello, ";
let str2 = "world!";
let greeting = str1.concat(str2);
  11. JS string method (toUpperCase)
    12. let str = "hello";
let upperCaseStr = str.toUpperCase();
  12. JS string method (slice)
    13. let str = "Hello, world!";
let slicedStr = str.slice(7);
  13. JS string method (indexOf)
    14. let str = "Hello, world!";
let index = str.indexOf("world");
  14. JS string method (replace)
    15. let str = "Hello, world!";
let newStr = str.replace("world", "mars");
  15. JS string method (split)
    16. let str = "apple, banana, orange";
let fruits = str.split(", ");
  16. JS object method (Object.keys)
    17. let person = {
name: "John",
age: 30,
city: "New York"
};
let keys = Object.keys(person);
  17. JS object method (Object.values)
    18. let person = {
name: "John",
age: 30,
city: "New York"
};
let values = Object.values(person);
  18. JS object method (Object.entries)
    19. let person = {
name: "John",
age: 30,
city: "New York"
};
let entries = Object.entries(person);
  19. JS Math object (Math.PI)
    20. let pi = Math.PI;
  20. JS Math object (Math.round)
    21. let rounded = Math.round(4.7);
  21. JS Math object (Math.floor)
    22. let roundedDown = Math.floor(4.7);
  22. JS Math object (Math.ceil)
    23. let roundedUp = Math.ceil(4.3);
  23. JS Math object (Math.random)
    24. let randomNumber = Math.random();
  24. JS Date object (new Date)
    25. let currentDate = new Date();
  25. JS Date object (getMonth)
    26. let month = currentDate.getMonth();
  26. JS Date object (getFullYear)
    27. let year = currentDate.getFullYear();
  27. JS Date object (getDay)
    28. let day = currentDate.getDay();
  28. JS Date object (getDate)
    29. let date = currentDate.getDate();
  29. JS Date object (getHours)
    30. let hours = currentDate.getHours();
  30. JS Date object (getMinutes)
    31. let minutes = currentDate.getMinutes();
  31. JS Date object (getSeconds)
    32. let seconds = currentDate.getSeconds();
  32. JS Date object (getMilliseconds)
    33. let milliseconds = currentDate.getMilliseconds();
  33. JS Date object (toDateString)
    34. let dateString = currentDate.toDateString();
  34. JS Date object (toISOString)
    35. let isoString = currentDate.toISOString();
  35. JS Date object (toLocaleDateString)
    36. let localeDateString = currentDate.toLocaleDateString();
  36. JS Date object (toLocaleTimeString)
    37. let localeTimeString = currentDate.toLocaleTimeString();
  37. JS Date object (toLocaleString)
    38. let localeString = currentDate.toLocaleString();
  38. JS Date object (UTC methods)
    39. let utcDate = currentDate.toUTCString();
  39. JS array method (forEach with index)
    40. let numbers = [1, 2, 3, 4, 5];
numbers.forEach(function(number, index) {
console.log("Index: " + index + ", Value: " + number);
});
  40. JS array method (map)
    41. let numbers = [1, 2, 3, 4, 5];
let doubled = numbers.map(function(number) {
return number * 2;
});
  41. JS array method (filter)
    42. let numbers = [1, 2, 3, 4, 5];
let evenNumbers = numbers.filter(function(number) {
return number % 2 === 0;
});
  42. JS array method (reduce)
    43. let numbers = [1, 2, 3, 4, 5];
let sum = numbers.reduce(function(accumulator, currentValue) {
return accumulator + currentValue;
}, 0);
  43. JS array method (every)
    44. let numbers = [2, 4, 6, 8, 10];
let allEven = numbers.every(function(number) {
return number % 2 === 0;
});
  44. JS array method (some)
    45. let numbers = [1, 2, 3, 4, 5];
let hasEven = numbers.some(function(number) {
return number % 2 === 0;
});