如果将输入数组元素在javascript中解析为整数，为什么会出现运行时错误？

Question

I was working on counting sort1 problem on hackerrank. I am using JavaScript to solve the problem.

Standard input is providing a number and an array which I was reading like this

var inp = input.split('\n')  

var n = parseInt(inp[0]);  //Number of elements
var ar = inp[1].split(' ').map(function(item){
    return parseInt(item);
});   //Array of numbers.

I was using above code in almost all of my solutions, it always worked. Then I process the above array ar in for loop which is giving runtime error in one of the test cases(last testcase).

for(var i = 0; i < n; i++) {
   var number = ar[i];
   //more code
}

But if I don't parse elements of the array using map function but parse them later in for loop, one by one, I don't get any error.

var ar = in[1].split(' ');   //Array of numbers in string format

for(var i = 0; i < n; i++) {
   var number = parseInt(ar[i]);
   //more code
}

Can Anyone explain Why?

Answer 1

in is a keyword, and you are trying to use it as a variable. I'm not sure why it says "Runtime Error", since this is actually a parsing error. Once renamed to something else, I could run the first two paragraphs error-free.

Answer 2

The only problem I remember having on Hackerrank that the .split() method often gave an empty string ( "" ) as the last element of the array. Probably that's why you failed on the last test case.

Make your logic like:

if(arr[i] !== "") 
    // perform operations
else 
    break;

Also, you can't use in as a identifier because it is a reserved keyword.