Multiplying array elements with for for loop

Question

I have been trying to write a function, where a for loop goes over an array with three numbers (bills), multiplies each array element depending on its value, and then returns the new array(tips), containing the multiplied values. I tried doing it with a for loop, however, the returned array only contains element number 2, while elements 0 and 1 return empty. Where am I going wrong? Thanks a lot for your help!

var bills = [10, 20, 40];

function tipCalc(arr) {
  var tips = [];
  for (i = 0; i < arr.length; i++) {
    if (arr[i] < 10) {
      tips[i] = arr[i] * 0.6;
    } else if (arr[i] > 10 && arr[i] < 20) {
      tips[i] = arr[i] * 0.5;
    } else if (arr[i] > 30) {
      tips[i] = arr[i] * 0.2;
    }
  }
  return tips;
}

console.log(tipCalc(bills))

Lazar Ljubenović · Accepted Answer · 2018-09-27 17:24:48Z

4

You're not covering all cases.

if (arr[i] < 10) {
  tips[i] = arr[i] * 0.6;
} else if (arr[i] > 10 && arr[i] < 20) {
  tips[i] = arr[i] * 0.5;
} else if (arr[i] > 30) {
  tips[i] = arr[i] * 0.2;
}

What if the item is exactly 10? What if the item is between 20 and 30? That will not be caught in any of the if-statements you've written here, which is probably why you're missing some elements in the returned array.

To see which one, you could write this:

if (arr[i] < 10) {
  tips[i] = arr[i] * 0.6;
} else if (arr[i] > 10 && arr[i] < 20) {
  tips[i] = arr[i] * 0.5;
} else if (arr[i] > 30) {
  tips[i] = arr[i] * 0.2;
} else {
  console.log('Oops! Unhandled case!', arr[i]);
}

answered Sep 27, 2018 at 17:24

Lazar Ljubenović

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Comments

ashish singh · Accepted Answer · 2018-09-27 17:26:12Z

1

error is you conditions dont handle arr[i] === 10 , you are handling <10 and >10 but not ===10, same with 20

try this

var bills = [10, 20, 40];

function tipCalc(arr) {
  var tips = [];
  for (i = 0; i < arr.length; i++) {
    if (arr[i] <= 10) {
      tips[i] = arr[i] * 0.6;
    } else if (arr[i] > 10 && arr[i] <= 20) {
      tips[i] = arr[i] * 0.5;
    } else if (arr[i] > 30) {
      tips[i] = arr[i] * 0.2;
    }
  }
  return tips;
}

console.log(tipCalc(bills))

edited Sep 27, 2018 at 17:26

answered Sep 27, 2018 at 17:25

ashish singh

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1 Comment

Lazar Ljubenović Over a year ago

Please highlight your changes and explain your answer instead of only posting code. That way, it's more useful for future visitors (and for the OP).

Amit chauhan · Accepted Answer · 2018-09-27 17:34:40Z

0

There is nothing wrong with your code you have just missed some conditions for 10 20

var bills = [10, 20, 40];

function tipCalc(arr) {
var tips = [];
for (i = 0; i < arr.length; i++) {
if (arr[i] < 10) {
  tips[i] = arr[i] * 0.6;
} else if (arr[i] >= 10 && arr[i] <= 20) {
  tips[i] = arr[i] * 0.5;
} else if (arr[i] > 30) {
  tips[i] = arr[i] * 0.2;
}
}
return tips;
}

console.log(tipCalc(bills))

answered Sep 27, 2018 at 17:34

Amit chauhan

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Comments

brk · Accepted Answer · 2018-09-27 17:38:39Z

0

You are not considering the case when the value is equal to 10 or 20

var bills = [10, 20, 40];

function tipCalc(arr) {
  var tips = [];
  for (var i = 0; i < arr.length; i++) {
    if (arr[i] <= 10) { //changed here
      tips[i] = arr[i] * 0.6;
    } else if (arr[i] > 10 && arr[i] <= 20) { //changed here
      tips[i] = arr[i] * 0.5;
    } else if (arr[i] > 30) {
      tips[i] = arr[i] * 0.2;
    }
  }
  return tips;
}

console.log(tipCalc(bills))

If you wish to avoid the if..else and local array variable you can use array map function

var bills = [10, 20, 40];

function tipCalc(arr) {
  return arr.map(function(item) {
    let m = 10 >= item ? 0.6 * item : 10 < item && 20 >= item ? 0.5 * item : 30 < item && (0.2 * item);
    return m
  })
}

console.log(tipCalc(bills))

edited Sep 27, 2018 at 17:38

answered Sep 27, 2018 at 17:27

brk

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1 Comment

Lazar Ljubenović Over a year ago

...or anything between 20 and 30, for that matter.

Chayan · Accepted Answer · 2018-09-27 17:39:20Z

0

var bills = [10, 20, 40];

function tipCalc(arr) {
  return arr.map(function(v){
  	return v <= 10 ? v * 0.6 : (v > 10 && v <= 20 ? v * 0.5 : v * 0.2);
  });

}

console.log(tipCalc(bills))

answered Sep 27, 2018 at 17:39

Chayan

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2 Comments

VladKhol Over a year ago

This works, but when I tried adding v> 30? v*0.2 to the last part of the ternary statement, instead if just : v * 0.2, the code stopped working. Could you explain why?

Chayan Over a year ago

@VladKhol Replace with this, although both output will be same. return v <= 10 ? v * 0.6 : (v > 10 && v <= 20 ? v * 0.5 : ( v > 30 ? v * 0.2 : v * 0.1 ));

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