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Reversing strings with a twist in JavaScript
We are required to write a JavaScript function that takes in a string str as the first argument and an integer num as the second argument.
Our function should reverse the first num characters for every 2 * num characters counting from the start of the string. And if there are less than num characters left, we have to reverse all of them.
If there are less than 2 * num but greater than or equal to num characters, then we have to reverse the first num characters and leave the other as original.
For example −
If the input string and the number are −
const str = 'klmnopq'; const num = 2;
Then the output should be −
const output = 'lkmnpoq';
There we reversed the first 2 of the first 4 characters then moved on to find we are only left with 3 characters so we reversed the first 2 of the 3 characters.
Example
The code for this will be −
const str = 'klmnopq';
const num = 2;
const reverseString = (str = '', num = 1) => {
if(str.length < num){
return str.split("").reverse().join("");
};
let res = "";
for(let i = 0; i < str.length; i += (2*num)){
res += str.split("").slice(i, i+num).reverse().join("");
res += str.slice(i+num, i+2*num);
};
return res;
};
console.log(reverseString(str, num));Output
And the output in the console will be −
lkmnpoq
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