Question

I have a countdown sequence i have to do for a code, when the result is entered it starts to countdown, i tried imputting some codes but i am clueless ( javascript):

/*******************************************************************************

* Problem 3: create count-down number sequence strings

*

* A count-down sequence is a String made up of a descending list of numbers.

* For example, the count-down sequence for the number 3 would be:

*

* "321"

*

* Write the countDownSequence function below, allowing any number between

* 1 and 10 to be accepted.  Otherwise, throw an error (see

* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)

*

* If we called countDownSequence(5) we'd expect to get:

*

* "54321"

*

* If we called countDownSequence(55) we'd expect to have an error thrown

*

* Error: only start values between 1 and 10 are valid

*

* @param {Number} start - the number to start counting down from (must be 10 or smaller).

******************************************************************************/

function countDownSequence(start) {

  var ret = '';

  while (start >= 0) {

    ret += start;

    if (start > 0) {

      ret += '';

    }

    start--;

  }

  return ret;

  // Your code here...

}

It has to pass these tests:

const { countDownSequence } = require('./solutions');

describe('Problem 3 - countDownSequence() function', function() {

  test('proper count down sequence from 10', function() {

    let start = 10;

    let result = countDownSequence(start);

    expect(result).toBe('10987654321');

  });

  test('proper count down sequence from 1', function() {

    let start = 1;

    let result = countDownSequence(start);

    expect(result).toBe('1');

  });

  test('starting at 0 should throw', function() {

    function shouldThrow() {

      // Using 0 is invalid, this should throw

      countDownSequence(0);

    }

    expect(shouldThrow).toThrow();

  });

  test('starting at a negative number should throw', function() {

    function shouldThrow() {

      // Using -100 is invalid, this should throw

      countDownSequence(-100);

    }

    expect(shouldThrow).toThrow();

  });

  test('starting at a number greater than 10 should throw', function() {

    function shouldThrow() {

      // Using 11 is invalid, this should throw

      countDownSequence(11);

    }

    expect(shouldThrow).toThrow();

  });

});

Answer 1

Try replacing the code of the function "countDownSequence()" with the below code and the code is as follows:

function countDownSequence(start) {

                        var ret = '';
                        try {
                                if (start >= 0 && start <= 10) {
                                        while(start >=0 ){
                                                ret += start;
                                                start--;
                                        }
                                        return ret;
                                }
                                else {
                                throw "Error: only start values between 1 and 10 are valid";
                                }
                        }catch(err){
                                console.log(err)
                        }
                        
                  
                }

This implementation of the countDownSequence should pass the test cases stated in the question.

I am attaching the output sample, I am just running the html file which contain the above code and calling the countDownSequence function with different parameter

If you face any problem let me know in the comment section. I will try to solve it.