3.1.3 • Published 9 years ago
argument-spec v3.1.3
argument-spec
A library to ease argument checking, especially complex arguments like options objects.
Usage
Node, Browserify
At command prompt
npm install argument-specIn code
argumentSpec = require('argument-spec');RequireJS
Download argument-spec.js from the most recent release at https://github.com/jrootham/argument-spec/releases and put it in your lib directory.
var argumentSpec = require('argument-spec');Script tag
<script type="text/javascript"
src="https://cdn.rawgit.com/jrootham/argument-spec/v3.1.0/argument-spec.js">
</script>Example of Use
var write = function(file, data, fetch) {
var fileSpec = {
name:argumentSpec.every([argumentSpec.length(10), '[a-z]+']) ,
extension: "jpg|gif"
};
var dataSpec = {
width: argumentSpec.range(20, 500),
height: argumentSpec.range(20, 500),
buffer: argumentSpec.instance(Buffer)
};
var errorArray = argumentSpec.validate('file', fileSpec, file);
errorArray = errorArray.concat(argumentSpec.validate('data', dataSpec, data));
errorArray = errorArray.concat(argumentSpec.validate('fetch', function(){}, fetch));
if (errorArray.length > 0) {
throw new Error(errorArray.join('\n'));
}
}Specification meanings
| Specification | Valid argument |
|---|---|
| undefined | anything |
| '' | string |
| 'regex' | string argument matching regex |
| 0 (or any number) | number |
| true (or false) | boolean |
| [] | any Array |
| spec | Array all of whose elements match spec |
| spec1, spec2, ... | Exact match for the array argument |
| function(a1,a2, ...) | Argument is function with matching number of arguments |
| {} | Any Object |
| {key1:spec, key2:spec2,...} | Object containing key1, key2,... where each property matches the corresponding spec. Keys are included in the name part of any error message. |
| argumentSpec.Base->{validate:function, spec:{key1:spec, key2:spec2,...}} | A function that validates an argument using a spec object (see below). |
Array and object specs nest.
Validation Functions
Functions and related specifications are defined as properties of objects created by the function argumentSpec.Base.
| Function | definition |
|---|---|
| some(spec1, spec2,...) | some spec is true for argument |
| every(spec1, spec2,...) | every spec is true for argument (useful for composing specs) |
| range(low, high) | numeric argument in low..high range (inclusive) |
| integer() | integer (fractional part is 0) |
| length(maxLength) | argument.length <= maxLength (argument.length must exist) |
| instance(object) | instanceof object |
| exact(object) | exact match for object properties, useful for options without defaults |
| optional(object) | permit missing properties in the argument, useful for options with defaults |
| isFalse() | argument is exactly false |
You can write your own validation functions. Here is an example:
/*
* Validation function that tests if the argument is an instance of another object
*/
var instance = function (thing) {
var instance = new Base();
instance.validate = function(name, argument) {
if (! (argument instanceof thing)) {
return [name + " is not an instance"]
}
return [];
}
return instance;
}