I use codefights and one of the solutions for finding if a string is palindrome or not is as follows:
PalindromeOrNot = s =>
s == [...s].reverse().join`` ? `Yes` : `No`
Here PalindromeOrNot is the function name and s is a parameter. I understand that the second line directly returns Yes or No but there is no return keyword used. Also, I have never seen such code anywhere else in Javascript. Can someone please explain.
Let's deconstruct this:
PalindromeOrNot = // an assignment
s => stmt // arrow notation, shorthand(*) for function (s) { return stmt; }
s == // ...where "stmt" is: a comparison
[...s] // array destructuring (turns s into an array of characters)
.reverse().join`` // reverse the array, join with the empty string
? // ternary operator (after the comparison)
`Yes` : `No` // results of the ternary, either 'Yes' or 'No',
// depending on whether the string equals its reverse
So in other words, this is a fancy way of writing
PalindromeOrNot = function (s) {
return s == s.split('').reverse().join('') ? 'Yes' : 'No';
}
On .join`` read this question: Backticks calling a function
(*) Almost. There is a difference between the regular functions and array functions when it comes to the handling of this.
It will be equivalent to this function:
PalindromeOrNot = function (s) {
return s == s.split('').reverse().join('') ? 'Yes' : 'No';
}
It just have some ES2015 sugar syntax like arrow functions (params) => expression, spread operator [...variable] and template literals `string text`.
