normalize-json

Terse syntax for validating and normalizing JavaScript objects in Node.

const nJ = require('normalize-json');

// a validator looks like this!
let validator = nJ({
    name: [String, 30], // a string with <= 30 characters
    age: [Number, 0, 100], // a number between 0 and 100, inclusive
    color: ['red', 'yellow', 'blue'] // must be one of these three values
});

// here's how we might validate/normalize an object
let obj = {
    name: ' Nigel   ', // this string will be trimmed!
    age: 23,
    color: 'blue',
    someUndefinedField: undefined // undefined fields will be stripped out
};

let normalizedObj = validator(obj); // 'normalizedObj' is a new object; 'obj' has not been changed
console.log(normalizedObj); // { name: 'Nigel', age: 23, color: 'blue' }

Try it out!

You can try out normalize-json in your browser at npm.runkit.com/normalize-json.

How to use

To validate an object, first define a validator for that type of object. This is done by passing an object into the nJ function. The keys of that object will be the names of the expected fields, and the values should be array literals with information on the expected ata.

Strings

let nameValidator = nJ({
    first: [ String ],
    last: [ String ]
});

After the validation process, strings will automatically be trimmed in the result object.

let name = { first: 'Don', last: 'Quixote    ' }
let normalizedName = nameValidator(name);
console.log(normalizedName.last); // 'Quixote'

If you only want to allow strings up to a certain length, use:

let tweetValidator = nJ({
    tweetBody: [ String, 140 ]
});

Numbers

let rotationValidator = nJ({
    degrees: [ Number, 0, 360 ] // minimum and maximum
});

If the minimum is 0, it can be omitted:

let rotationValidator = nJ({
    degrees: [ Number, 360 ] // minimum and maximum
});

If there's no upper or lower bound to validate, you can either specify -Infinity and Infinity, or just leave them out entirely.

Integers

Similar to Numbers:

let colorValidator = nJ({
    red: [ Number.isInteger, 0, 255 ],
    green: [ Number.isInteger, 0, 255 ],
    blue: [ Number.isInteger, 0, 255 ]
});

Enumerations

let moodValidator = nJ({
    mood: [ 'happy', 'sad', 'excited', 'scared' ]
});

Simply pass all allowed values as an array. Works with strings, numbers, booleans, or a mix of the three.

Regular Expressions

let phoneNumberValidator = nJ({
    areaCode: [ /\(\d{3}\)/ ],
    number: [ /\d{3}-\d{4}/ ]
});

Simply pass the regular expression literal in an array.