Improve the given code below, making sure that the code will require input from the user:
Problem: Write a JavaScript function that accepts any number and returns the square of that number.
const square = (a) => {
var res = 1;
res = a * a;
console.log("Num1 ");
console.log("Square of " + a + " is: " + res);
console.log("In");
}
square(5);