Runtime Argument Test

We are always check the arguments in every function, such as below:

function get(name) {
    if (!name || !name.length) {
        throw new Error('name is empty');
    }

    // code body
}

funtion set(config) {
    if (typeof config !== 'object') {
        throw new Error('config must be an object');
    }

    if (!config.prop1) {
        throw new Error('must provide config.prop1');
    }

    if (!typeof config.prop2 !== 'number') {
        throw new Error('config.prop2 must be a number');
    }

    // code body
}

These checks are annoying but indispensable.

This tool provide a unified assertion checking for your project, like below:

var expect = require('expect');
function get(name) {
    expect(name).isString().notEmpty();

    // code body
}

funtion set(config) {
    expect(config).isObject()
        .has('prop1')
        .has( { 'prop2' :  Number} );

    //code body
}

If any condition fail, it will throw error. (or any custom event).

The tool has very tiny size, and easily to use, especially in node.js .

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How to Use

NodeJS: install via npm:

npm install args-expect

Browser:

copy lib/args-expect-min.js to your project folder

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API List

1. expect(obj).isElement();

2. expect(obj).isObject()

3. expect(obj).isArray()

4. expect(obj).isFunction()

5. expect(obj).isBoolean()

6. expect(obj).isNull()

   • return true, if obj is null or undefined

7. expect(obj).isEmpty()

   • check if obj is null or undefined, or is string / array but has zero length.

8. expect(obj).notNull()

9. expect(obj).notEmpty()

10. expect(obj).toEqual( value )

11. expect(obj).is( type [,...] )

    • check if obj is match any of incoming types.

        expect(obj).is( String, Object ) // expect the object is String or Object
        expect(obj).is( CustomizeClass ) // expect the object is instance of CustomizeClass
      

12. expect(obj).has(propName)

    • check if obj is an Object and has all specified properties.

        expect(obj).has('key');
        expect(obj).has(['key', 'prop1']);
      

    • check if obj has all specified properties and match the given types.

        expect(obj).has({
                key: String,
                prop1: Number
           })
      

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Check Multi Args

expect.all(1, 2, 3).isNumber();

use expect.all() to check multi arguments with one line

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Error Report Method

The default report method will throw error.

We can use mode() to create new expect obj with new report method:

// create a new expect object with log report.
var expect = require('expect').mode('log');

expect('123').isString();
// if any condition fail, it will log warning message on console

Or use any custom event

// create a new expect object with alert report
var expect = require('expect').mode(function(msg) {
    alert(msg);
});

expect('123').isString(); // it will alert warning message.

Since mode() will create new expect instance, We can use disable() to disable all instance at one shot.

require('excpet').disable();

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Get The Check Result

// disable the report mode
expect = expect.mode('none');
var result = expect(1).isString();

alert(expect.rejected);

use result.rejected to get the check result.

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Module Standard Supported

This tool is support CommonJS, AMD, KMD, module standard.

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Questions?

If you have any questions, feel free to create a new issue.