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Shift last given number of elements to front of array JavaScript
Let’s say, we have to write an Array function, say prependN() that takes in a number n (n <= length of array the function is used with) and it takes n elements from the end and puts them in front of the array.
We have to do this in place and the function should only return a boolean based on the successful completion or failure of the task.
For example −
// if the input array is: const arr = ["blue", "red", "green", "orange", "yellow", "magenta", "cyan"]; // and the number n is 3, // then the array should be reshuffled like: const output = ["yellow", "magenta", "cyan", "blue", "red", "green", "orange"]; // and the return value of function should be true
Now, let’s write the code for this function −
Example
const arr = ["blue", "red", "green", "orange", "yellow", "magenta",
"cyan"];
Array.prototype.reshuffle = function(num){
const { length: len } = this;
if(num > len){
return false;
};
const deleted = this.splice(len - num, num);
this.unshift(...deleted);
return true;
};
console.log(arr.reshuffle(4));
console.log(arr);Output
The output in the console will be −
true [ 'orange', 'yellow', 'magenta', 'cyan', 'blue', 'red', 'green' ]
Updated on: 28-Aug-2020
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