Calculate Percentage

calculatePercentage

The calculatePercentage function performs various percentage-related calculations based on the specified mode and input values. It supports operations such as computing percentages, values from percentages, original values, percentage changes, applying percentage changes, percentage differences, and inverse percentages.

Function Signature

function calculatePercentage(options: PercentageOptions): number

Parameters

options (PercentageOptions): An object specifying the calculation mode, the necessary input values, and an optional rounding precision.

Modes & Parameters (Options)

All modes support an optional roundTo (number) property, which determines the number of decimal places to round the result to if it's a float. Defaults to 3.

Examples by Mode

playground.ts

Type Definitions

type PercentageOptions = (
  | GetPercentOptions
  | GetValueOptions
  | GetOriginalOptions
  | GetChangeOptions
  | ApplyChangeOptions
  | GetDifferenceOptions
  | InversePercentageOptions
) & {
  roundTo?: number;
};

interface GetPercentOptions {
  mode: 'get-percent';
  part: number;
  total: number;
}

interface GetValueOptions {
  mode: 'get-value';
  percentage: number;
  total: number;
}

interface GetOriginalOptions {
  mode: 'get-original';
  percentage: number;
  value: number;
}

interface GetChangeOptions {
  mode: 'get-change-percent';
  oldValue: number;
  newValue: number;
}

interface ApplyChangeOptions {
  mode: 'apply-percent-change';
  baseValue: number;
  percentage: number;
}

interface GetDifferenceOptions {
  mode: 'get-percent-difference';
  value1: number;
  value2: number;
}

interface InversePercentageOptions {
  mode: 'inverse-percent';
  part: number;
  total: number;
}

Notes

The function ensures that inputs are valid numbers before performing calculations.
For percentage change calculations, if the oldValue is zero, the function returns NaN to avoid division by zero.
It assumes that all input values are finite numbers; passing Infinity or NaN as inputs will result in NaN outputs.