Narrowly Preventing Mayhem


    0.1.5 • Public • Published


    Immutable Error provides harmonized error generator for modules in the Immutable App ecosystem.

    Creating a new error generator instance

    var immutableError = new ImmutableError({
        class: 'Foo',
        errorCodes: {
            100: 'foo error'
        nameProperty: 'foo',

    ImmutableError must be instantiated with an object containing the configuration options for the error generator.

    The class property will be used as a prefix for all error messages.

    The codes object defines a mapping of error codes to default error messages. Error codes must start at a number grater than 100 with a maximum length of three digits.

    The nameProperty property will be used to get the name of the instance that the error occured with if both are set.


    var error = immutableError.error(this, 100, 'foo error', err, {foo: true})

    The error method generates and returns a new Error.

    The arguments to error are:

    • instance - the instance (this) context that the error occurred in
    • code - the error code
    • message - a custom error message
    • error - the original Error object if re-throwing a caught error
    • data - any additional error data to include

    All arguments are optional and an error will always be generated.


    immutableError.assert(foo === true, this, 100)

    The assert method will evaluate its first argument and throw an error if it does not evaluate as truthy.

    The subsequent arguments to assert will be passed to error to generate the Error.

    Unlike error the assert method will throw the Error.


    immutableError.throw(this, 100)

    The throw method calls error with the passed arguments and throws the generated error.

    Generating an error without an instance

    var error = immutableError.error(null, 100)

    If an error is being generated outside of the context of a specific class instance then null should be passed as the first argument.

    Generating an error without a code

    var error = immutableError.error(this, null, 'foo')

    If a code is not available for the error null or 0 should be used.

    Generating an error with a custom error message

    var error = immutableError.error(this, 100, 'custom error message')

    A custom error can be passed as the third argument. If this argument is not a string it will not be used.

    Generating an error from an existing error object

    try {
    } catch (err) {
        var error = immutableError.error(this, 100, null, err)

    When catching and rethrowing an error pass the original error as the fourth argument and it will be added to the data of the error that is generated.

    Error codes

    The error codes defined by modules must be three digits starting with 100.

    The error code will be used to lookup the default message for the error.

    For registered classes the error code will be appended to a two digit prefix that identifies the class that generated the error.

    If the class generating the error is not registered then the error code will always be 10000.

    For classes that are registered where an error code is not specified the error code will be the class prefix followed by three zeros.

    The three digit error code will always be stored in

    Registered classes

    base code class
    20000 ImmutableAppComponent




    npm i immutable-error

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