on-error
Generate error-first callback handlers naturally.
Handle errors via a dedicated error handler function, or by emitting them.
Optionally invoke a 2nd function on no error, or regardless of error.
Potentially reduce the number of branches needing tests.
examples
var onError = require('on-error')
function handleIt (err) {}
failToDoSomething(onError(handleIt))
failToDoSomething(onError.emit(emitter))
doSomething(onError(handleIt).otherwise(function (message) {
console.log('will see this: %s', message)
}))
failToDoSomething(onError(handleIt).otherwise(function (message) {
console.log('will NOT see this: %s', message)
}))
failToDoSomething(onError(handleIt).always(function (message) {
console.log('will see this too: %s', message)
}))
failToDoSomething(onError(handleIt).alwaysWithError(function (err, message) {
console.log('will see this too (with the error): %s, %s', err, message)
}))
var emitter = new EventEmitter().on('error', console.log)
failToDoSomething(onError.emit(emitter).otherwise(function (message) {
}))
doSomething(onError(reject).otherwise(resolve))
api
var onError = require('on-error')
onError(cb)
Returns a function that when called with a truthy first argument, will execute cb
with said argument.
onError.emit(emitter)
Returns a function that when called with a truthy first argument, will emit error
on the provided event emitter
with said argument.
onError(cb1).otherwise(cb2)
Returns a function that when called with a truthy first argument, will execute cb1
with said argument. When executed with a non-truthy 1st argument, cb2
will instead be executed with the error argument stripped.
.otherwise
may also be chained from onError.emit()
onError(cb1).otherwiseWithError(cb2)
Returns a function that when called with a truthy first argument, will execute cb1
with said argument. When executed with a non-truthy 1st argument, cb2
will instead be executed with the error argument in-tact.
.otherwiseWithError
may also be chained from onError.emit()
onError(cb1).always(cb2)
Returns a function that when called with a truthy first argument, will execute cb1
with said argument. In addition, cb2
will always be executed with the error argument stripped.
.always
may also be chained from onError.emit()
onError(cb1).alwaysWithError(cb2)
Returns a function that when called with a truthy first argument, will execute cb1
with said argument. In addition, cb2
will always be executed with the error argument in-tact.
.alwaysWithError
may also be chained from onError.emit()
testing
npm test [--dot | --spec] [--grep=pattern]
Specifying --dot
or --spec
will change the output from the default TAP style.
Specifying --grep
will only run the test files that match the given pattern.
coverage
npm run coverage [--html]
This will output a textual coverage report. Including --html
will also open an HTML coverage report in the default browser.