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whatif

A conditional-statement based programming pattern

The goal of whatIf is to write readable, self explanatory code by writing code using plain English inside conditional statements.

whatIf reduces promises and functions until it gets a values. If the result is true it will execute the .then's associated to the statement, if not it will continue to the .butWhatIf statements until it finds a matching, if not it will run the .otherwise statement.

examples

The basics:

whatIf(theUserLogins)
.then(redirectTheUserToTheDashboard)
.otherwise(displayAnErrorMessage);

You can pass logical operators:

whatIf(theThemeColor === 'red')
.then(displayTheRedDashboard)
.butWhatIf(theThemeColor === 'blue')
.then(displayTheBlueDashboard)
.otherwise(displayTheGreenDashboard);

Or even promises:

whatIf(weFetchTheDashboardData())
.then(displayTheDashboardData)
.otherwise(displayAnErrorMessage);

Specifications:

Warning: these may change in the near future. Not ready for production.

WhatIf can accept:

  • Boolean values whatIf(fruit === 'apple').
  • Function references whatIf(canEatFruits).
  • Promises whatIf(Promises.resolve(true)).

Note: Promises that return an error will be treated as falsy values. It is recommended to handle errors before passing the promise to whatIf or .butWhatIf.

WhatIf can have multiple conditions in a if, if-else fashion:

whatIf(falseStatement)
.then(thisWillNotExecute)
.butWhatIf(truthfulStatement)
.then(thisWillExecute);

What if can have a default statement, like an else:

whatIf(falseStatement)
.then(thisWillNotExecute)
.butWhatIf(anotherFalseStatement)
.then(thisWillNotExecuteEither)
.otherwise(thisWillExecute);

Can use .and instead of .then

whatIf(userIsAdmin)
.then(displayAdminMenu)
.and(displayAdminReport);

Can catch errors that happen inside .then and ..and statements:

whatIf(theUserHasLoggedIn)
.then(tryToRedirectThemToTheirDashboard)
.catch(tryToHandleTheRedirectionError);

But will treat errors thrown inside whatIf and .butWhatIf statements as falsy values:

whatIf(thisThrowsAnError)
.then(thisWillNotExecute)
.catch(thisWillNotExecuteEither)
.otherwise(thisWillExecute);