wentto

GOTO in Javascripts. Considered harmful.

Getting Started

Install the module with: npm install wentto

var wentto = require('wentto');

var doSomethingComplicated = wentto([
    function preCheck(go) {
        if (something) { return go('fail') }
        else if (somethingElse) { return go('fail') }
    },
    function doTheThing(go) {
        // Do the thing...
    },
    ['fail', function fail(go) {
        // Handle errors here
    }]
])

Documentation

require('wentto')([func0, func1, func2, func3, ...])

Pass it an array of functions. Make sure all of them accept the function "go" as a parameter.

wentto returns a function. That function will execute func0, then func1, etc. If one of these functions returns go(<index>), execution continues at func<index>.

return go(index)

Go to a function. The index argument is the index of the function in the array you passed to wentto(). So return go(0) to go back to the first function, return go(2) to go to the second function.

return go(label)

Go to a function which has a name. See the example below, "naming your goto labels", to see how to give your functions a name.

return go(indexOrLabel, args...)

Calls the next function (see the 2 above entries) with the arguments you passed.

Examples

achieving a loop

var a = 0;
var doSomethingUntil = wentto([
    function doSomething(go) {
        a += 1;
    },
    function until(go) {
        if (a < 3) {
            return go(0);
        }
    }
])

doSomethingUntil();

a // -> 3

accepting parameters

just add them to every function after the "go" param

var justSum = wentto([
    function (go, a, b) {
        return a + b;
    },
])

justSum(1, 2) // -> 3

returning early

Just return anything which is not undefined or go(somewhere)

var dontGoFar = wentto([
    function (go) { return 42 },
    function neverExecuted(go) {}
])

naming your goto labels

It can become complicated to deal with numeric indices in a large wentto chain.

To give names to your functions, just wrap them in a pair ([name, yourFunction]). You don't have to give a name to every function.

var myFunc = wentto([
    function (go) { if (something) return go('fail') },
    ['fail', function (go) { throw something }]
])

How does it work?

It's just a for loop which executes the input functions one by one. go is actually a class which wraps the index of the function you want to go to. If one of the functions returns an instance of go, the loop variable is changed (i = newIndex + 1; continue;).

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using Grunt.

Release History

• 0.0.4 Passing arguments to the next function
• 0.0.3 Documentation fix
• 0.0.2 Adds the possibility of naming each function in the wentto() chain.
• 0.0.1 Implemented core functionality: passing an array of functions and using go() to goto other functions.

License

Copyright (c) 2014 Fábio Santos. Licensed under the MIT license.