Created
February 22, 2022 09:55
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Palyndrome dates generator (Javascript)
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function palindrome(str) { | |
// Step 1. Lowercase the string and use the RegExp to remove unwanted characters from it | |
var re = /[\W_]/g; // or var re = /[^A-Za-z0-9]/g; | |
var lowRegStr = str.toLowerCase().replace(re, ''); | |
// str.toLowerCase() = "A man, a plan, a canal. Panama".toLowerCase() = "a man, a plan, a canal. panama" | |
// str.replace(/[\W_]/g, '') = "a man, a plan, a canal. panama".replace(/[\W_]/g, '') = "amanaplanacanalpanama" | |
// var lowRegStr = "amanaplanacanalpanama"; | |
// Step 2. Use the same chaining methods with built-in functions from the previous article 'Three Ways to Reverse a String in JavaScript' | |
var reverseStr = lowRegStr.split('').reverse().join(''); | |
// lowRegStr.split('') = "amanaplanacanalpanama".split('') = ["a", "m", "a", "n", "a", "p", "l", "a", "n", "a", "c", "a", "n", "a", "l", "p", "a", "n", "a", "m", "a"] | |
// ["a", "m", "a", "n", "a", "p", "l", "a", "n", "a", "c", "a", "n", "a", "l", "p", "a", "n", "a", "m", "a"].reverse() = ["a", "m", "a", "n", "a", "p", "l", "a", "n", "a", "c", "a", "n", "a", "l", "p", "a", "n", "a", "m", "a"] | |
// ["a", "m", "a", "n", "a", "p", "l", "a", "n", "a", "c", "a", "n", "a", "l", "p", "a", "n", "a", "m", "a"].join('') = "amanaplanacanalpanama" | |
// So, "amanaplanacanalpanama".split('').reverse().join('') = "amanaplanacanalpanama"; | |
// And, var reverseStr = "amanaplanacanalpanama"; | |
// Step 3. Check if reverseStr is strictly equals to lowRegStr and return a Boolean | |
return reverseStr === lowRegStr; // "amanaplanacanalpanama" === "amanaplanacanalpanama"? => true | |
} | |
// Returns an array of dates between the two dates | |
function getDates (startDate, endDate) { | |
const dates = [] | |
let currentDate = startDate | |
const addDays = function (days) { | |
const date = new Date(this.valueOf()) | |
date.setDate(date.getDate() + days) | |
return date | |
} | |
while (currentDate <= endDate) { | |
dates.push(currentDate) | |
currentDate = addDays.call(currentDate, 1) | |
} | |
return dates | |
} | |
function padTo2Digits(num) { | |
return num.toString().padStart(2, '0'); | |
} | |
function formatDate(date) { | |
return [ | |
padTo2Digits(date.getDate()), | |
padTo2Digits(date.getMonth() + 1), | |
date.getFullYear(), | |
].join('/'); | |
} | |
const dates = getDates(new Date(2022, 02, 22), new Date(3001, 03, 10)) | |
dates.forEach(function (date) { | |
if ( palindrome( formatDate(date) ) ) | |
console.log( formatDate(date) ); | |
}); |
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