zwitch
Handle values based on a property.
Install
npm:
npm install zwitch
Use
var zwitch = require('zwitch')
var handle = zwitch('type')
handle.invalid = invalid
handle.unknown = unknown
handle.handlers.alpha = handle
handle({type: 'alpha'})
Or, with a switch statement:
function handle(value) {
var fn
if (!value || typeof value !== 'object' || !('type' in value)) {
fn = invalid
} else {
switch (value.type) {
case 'alpha':
fn = handle
break
default:
fn = unknown
break
}
}
return fn.apply(this, arguments)
}
handle({type: 'alpha'})
API
zwitch(key[, options])
Create a functional switch, based on a key (string).
options
Options can be omitted and added later to one.
handlers(Object.<Function>, optional) — Object mapping values to handle, stored onone.handlersinvalid(Function, optional) — Handle values withoutkey, stored onone.invalidunknown(Function, optional) — Handle values with an unhandledkey, stored onone.unknown
Returns
Function — See one.
one(value[, rest...])
Handle one value. Based on the bound key, a respective handler will be
invoked.
If value is not an object, or doesn’t have a key property, the special
“invalid” handler will be invoked.
If value has an unknown key, the special “unknown” handler will be invoked.
All arguments, and the context object, are passed through to the handler, and it’s result is returned.
one.handlers
Map of handlers (Object.<string, Function>).
one.invalid
Special handler invoked if a value doesn’t have a key property.
If not set, undefined is returned for invalid values.
one.unknown
Special handler invoked if a value does not have a matching
handler.
If not set, undefined is returned for unknown values.
function handler(value[, rest...])
Handle one value.
Related
mapz— Functional map