FailFast

You can use FailFast to safeguard functions from bad input, and giving the caller an early warning that bad input is being passed.

// define a function, using FailFast to protect itself from bad input
function myFunction( myParam ){
        FailFast.assert.isNumber( 'myParam must be a number, you passed: ' + myParam, myParam );
        // your real code here
}

// call the function with bad input
myFunction( 'lorem ipsum' );

// throws Error with message property of
// "myParam must be a number, you passed: lorem ipsum"
// the execution will be halted, and the developer will immediately see
// what he's done wrong

Implemented methods

• FailFast.assert
• FailFast.assert.isNotNull
• FailFast.assert.isBoolean
• FailFast.assert.isString
• FailFast.assert.isArray
• FailFast.assert.isFunction
• FailFast.assert.isDate
• FailFast.assert.isNumber
• FailFast.assert.isNormalNumber
• FailFast.assert.isObject
• FailFast.assert.hasProperty
• FailFast.assert.match

More reading about failing fast

• FailFast introduction
• FailFast on Wikipedia
• C2 Wiki about FailFast

Testing

The tests are done using BusterJS and the excellent Sinon.JS.

Future of FailFast

• Build script to create the following wrappers
  • jQuery plugin
  • Ender.js wrapper
• More extensive examples of good use

Versioning

FailFast uses Semantic Versioning for predictable versioning.

Changelog

• v2.0
  • Got rid of the mandatory msg argument, as it lead to a lot of repetition for very little value
  • Grouping all functions under the assert function, should be familiar for users of Buster.JS
  • Exposing the fail function, to make it easy for users to create custom assertions

License

MIT: http://mrgnrdrck.mit-license.org