Javascript - A smarter way to write a function that uses a lot of conditional statements to return incremental values based on a different number ranges?

taylor018
August 16, 2023
93 views
1 vote
2 Answers

I’m trying to write a function to return a certain value if the input is between a certain number range.

Normally, I would just write a series of if/else if statements to do the job. But, I’m working with a large number of ranges so writing out 30+ if/else if statements seems inefficient.

Let’s say I have a set min and max number for the overall range and I want to break that up into smaller ranges. For each range, I want to return some value. Ideally, the return value for each range will decrease by some set number.

For context, I’m trying to use something similar to this to calculate a value based on mileage. For example, if the mileage is between 101-120 miles, the rate is equal to 80% of the mileage. As the mileage increases, the percentage decreases. And, the number that the percentage decreases by can be some set number (-0.05 for example)

...
else if (m >= 101 && m <= 120) return 0.80
else if (m >= 121 && m <= 140) return 0.75
...

Since there is a pattern to the return values for each range, I’m thinking this can be done in a better way than just writing out a bunch of if/else statements but I’m not sure exactly how that can be done. Any ideas?

Tags: conditional-statements javascript

Answers

Your example doesnt increment by 15; so, I’m assuming that was a typo.

The solution I would use is a function.
ie.

(() => {

// in your example you have it .95 -> .9 -> .85 thus this starts at 1.
const STARTING_RETURN_VALUE = 1;

// the range increment your if statement has is 15
const INCREMENT = 15;

// this is the value in which the return value decreases by per interval
const DECREASING_RETURN_VALUE = .05;

const getReturn = (x, increment, starting_return_value, decreasing_return_value) => {
     return starting_return_value - (Math.floor(x/increment)+1)*decreasing_return_value;
}

console.log(getReturn(29, INCREMENT, STARTING_RETURN_VALUE, DECREASING_RETURN_VALUE));

})();

something like that ?

console.log('112->', computeRate( 0.95, 0.05, 100, 20, 112 )); // 0,9
console.log('133->', computeRate( 0.95, 0.05, 100, 20, 133 )); // 0,85
console.log('164->', computeRate( 0.95, 0.05, 100, 20, 164 )); // 0,75
console.log('250->', computeRate( 0.95, 0.05, 100, 20, 250 )); // 0,55 


function computeRate( base, baseDec, toptest, step, value )
  {
  let min  = 0
    , max  = toptest
    , resp = base
    ;
  while ( (!(value >= min && value <= max)) && resp > 0)
    {
    min  += step; // min += step +1;  is not necessary;
    max  += step;
    resp -= baseDec;
    resp = resp.toFixed(2);  // to fix float numbers matters
    }
  return Number.parseFloat(resp);
  }

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Javascript – A smarter way to write a function that uses a lot of conditional statements to return incremental values based on a different number ranges?

Answers