Useful JavaScript (JS) or jQuery snippets for day-to-day Software Development

javascript_code_snippets_for_day_today_work.js

// detect the Enter key in a text input field

$(".input1").on('keyup', function (e) {
    if (e.keyCode === 13) {
        // Do something
    }
});

// array for..of cycle
// tip: you can stop iterating at any time using a break statement.
const colors = ['blue', 'green', 'white'];

for (const color of colors) {
  console.log(color);
}
// 'blue'
// 'green'
// 'white'

/*
* for cycle
* tip: you can stop iterating at any time using a break statement.
*/
const colors = ['blue', 'green', 'white'];

for (let index = 0; index < colors.length; index++) {
  const color = colors[index];
  console.log(color);
}
// 'blue'
// 'green'
// 'white'

/*
 * array.forEach() method
 * tip: you cannot break array.forEach() iterating
 */
const colors = ['blue', 'green', 'white'];

colors.forEach(function callback(value, index) {
  console.log(value, index);
});
// 'blue', 0
// 'green', 1
// 'white', 2

/*
 * array.map() method
 */
const numbers = [0, 2, 4];

const newNumbers = numbers.map(function increment(number) {
  return number + 1;
});

console.log(newNumbers) 
// => [1, 3, 5]

/*
 * Array.from() function
 */
const numbers = [0, 2, 4];

const newNumbers = Array.from(numbers,
  function increment(number) {
    return number + 1;
  }
);

console.log(newNumbers); 
// => [1, 3, 5]

/*
 * array.reduce() method 
 */

const numbers = [2, 0, 4];

function summarize(accumulator, number) {
  return accumulator + number;
}

const sum = numbers.reduce(summarize, 0);

console.log(sum); // => 6

/*
 * check-whether-a-string-contains-a-substring 
 */
// ECMAScript 6

var string = "foo",
    substring = "oo";

console.log(string.includes(substring));

// in ECMAScript 5 or older environments, use String.prototype.indexOf, which returns -1 when a substring cannot be found

var string = "foo",
    substring = "oo";

console.log(string.indexOf(substring) !== -1);

// to break string by some value in it and make it as an array make use of string.prototype.split
// note: it doesn't change the string value and just output

let str = "https://www.google.com/a/b/c";
str.split('/'); // ["https:", "", "www.google.com", "a", "b", "c"]

// To add value at the front of the array use unshift
// array unshift in javascript function returns the new length or total number of items in the array in this case 4

let numbers = [2, 3, 4];
numbers.unshift(1)
console.log(numbers)

// javascript array shift
// The shift() method removes the first element from an array and returns that removed element. 
// This method changes the length of the array.

const array1 = [1, 2, 3];

const firstElement = array1.shift();

console.log(array1);
// expected output: Array [2, 3]

console.log(firstElement);
// expected output: 1