just-fns

Just functions

This is a collection of functions for performing various calculations for cycling related data, as found on Strava, TrainingPeaks and TrainerRoad. I am using them in araceathlete.com and wanted to break this out into its own module for "simplicity". Most of these are used in the view for converting raw data into something user friendly.

The functions are broken down into three parts:

Helpers: These are just basic functions for shaping data returns that I was doing in multiple places.

Measurement Conversion: These take a measurement and convert it to some other measurement.

Cycling: These are cycling specific functions for returning other metrics. I've formulated them based on information I have found at Strava, TrainingPeaks, TrainerRoad and others into JavaScript. From my testing, they return the same values Strava would return given the same input. For example, using calcTssScore and a mongodb aggregation to exponentially calculate Fitness over three years of activity returns the same Fitness and Fatigue numbers as the Strava chart.

Helpers

Capitalize and Space

Takes strings with Spaces, Hyphens and Underscores and returns all as spaces. Then upper case the first character. Used to make Tag strings look nice.

capAndSpace(string: String);

capAndSpace('123_hello-world'); // returns 123 Hello World

CSV String to Array

Takes a string of comma separated values and returns an array. Used for meta tag strings in Gatsbyjs

csvStringToArray(string: String);

csvStringToArray("patience, time, get it right") // returns ["patience", "time", "get it right"]

Divide and Round

Takes two numbers and divides and rounds the result.

divideAndRound(dividend: Number, divisor: Number, places: Number)

divideAndRound(190, 240, 2); // returns 0.79

Get Value for Specific Key in Last Element of an Array of Objects

Takes an array of objects and returns the last value of the key_name from the last element.

getLastInArray(arrOfObj: Array, key_name: String)

const arr = [
  { weight: 160, age: 27 },
  { weight: 165, age: 28 },
  { weight: 168, age: 29 },
];

getLastInArray(arr, 'weight'); // returns 168

Highest Consecutive Average

Finds the highest consecutive average of a specified number of elements in an array. For instance, could be used to find the highest heart rate over five seconds in a Stava Activity Stream.

If the arguments passed are not actionable, expect it to return null.

hiConsAvg(arr: Array, elements: Integer)

hiConsAvg([2.55, 3, 3, 2.3, 2, 4], 3); // returns 2.85

Round

Just rounds numbers.

round(number: Number, places: Number)

round(1.535, 2); // returns 1.54

Seconds to Time

Takes seconds and converts them to human readable time. Returns seconds as Days, Hours and Minutes.

secondsToTime(seconds: Number)

secondsToTime(5847708); // returns 67 days 16:21

Measurement Conversion

These all work the same and the units seem self explanatory. For example kgToPounds returns Lbs from a number of Kilograms. These also include round options.

kgToPounds(kilograms: Number)

kgToPoundsRound(kilograms: Number, places: Number)

These include:

• kgToPounds - Kilograms to Pounds
• metersToFeet - Meters to Feet
• metersToMiles - Meters to Miles
• metersToKm - Meters to Kilometers
• mpsToKPH - Meters per second to Kilometers per hour
• mpsToMPH - Meters per second to Miles per hour

kgToPounds(8); // returns 17.63696
kgToPoundsRound(8, 3); // returns 17.637
kgToPoundsRound(8); // returns 18

Cycling

Altitude Index

Altitude Index takes the planned altitude and user altitude in Meters and returns the index used for calculating percent of FTP at altitude. It was added to simplify input of percentFTPAcc and percentFTPNAcc below. It may be used in future versions of Difficulty Index to add weight to the difference in altitude on a per user basis.

altitudeIndex(altitude: Number, userAltitude: Number)

altitudeIndex(500, 24.575);  // returns 0.25425

Percent of FTP at Altitude

These two functions deal with relative FTP at a specific altitude. The first for an Acclimatized Athlete, the second for Non-Acclimatized Athlete. For more information see this blog post: araceathlete.com/blog/power-at-altitude/

percentFTPAcc(altitude: Number - (userAltitude: Number * 0.01)

• percentFTPAcc - Acclimatized Athlete
• percentFTPNAcc - Non-Acclimatized Athlete

percentFTPAcc(altitudeIndex(500, 24.575)); // returns 99.34452477

Calculate TSS Score

These functions calculate TSS based activity Elapsed Time and Athletes FTP. For more information on TSS and FTP see these blog posts here: Power

calcTssScore(elapsed_time: Number, weighted_average_watts: Number, ftp: Number)

• calcTssScore
• calcTssScoreRound

calcTssScoreRound(29377, 205, 253); // returns 535.76

Difficulty Index

Difficulty index is a new calculation based on Distance and Elevation. It lets a Athlete compare previously known activities and a route to help them decide if it seems reasonable to them.

difficultyIndex(totalEleGain: Number, distance: Number)

difficultyIndex(2000, 90000); // returns 4.44

Do Not Use

These functions handle prepping data for display and are too specialized for reuse or their own good. They will probably be depreciated. Not covered by tests.

• statsConversions
• mPrefLabel

Testing

• npm test Runs all tests.
• npm run test:src only runs the tests in src in watch mode.

Add, Commit, Version

Since the branch must be clean to version and publish, we need to:

• add and commit, which will:
• Run linting and tests because of pre-commit hooks.

git commit -am 'some totally useful comment'

Next, we need to run:

• version, which will:
• Rerun linting and tests
• Transpile the JavaScript with babel
• Git add the dst directory and package.json using the version number as the commit message
• Push the changes to Github
• Publish to npm
• Delete the dst directory

npm version <major | minor | patch>