Neighborly Package Megalodon


    1.2.0 • Public • Published


    Parameter validation for builtins and custom types. Accepts params and a schema and returns an array of Errors or false.

    var validate = require('validate-params-schema')
    function hi(params, callback) {
      var schema = {
        'name':       {required:true,  type:Object},
        'name.first': {required:true,  type:String},
        'name.last':  {required:false, type:String}
      var errors = validate(params, schema) 
      if (errors) {
      else {
        callback(null, 'hi ' + params.first)
    // logs: null, hi brian
    hi({name:{first:'brian', last:'leroux'}}, console.log)
    // logs: [ [ReferenceError: missing required param name.first] ] 
    hi({name:{}}, console.log)


    • For testing an Object that presumably came from a JSON payload
    • Thusly, primarily concerned with JSON value types: Object, String, Number, Array and Boolean
    • Custom types are easily supported (see ./examples)
    • Designed to test keys and nested keys
    • Optionally validate required
    • Optionally validate min and max for String, Number and Array builtin types (and easily implement for custom types)

    things it does not do

    • mutate things with: serialization, formatting or defaults
    • nested subtypes (eg. the things in an array)
    • localized error messages

    further justifications

    There are a tonne of libraries that do things like this but also do a whole lot more. This library deliberately limits its scope: make errback style param contract validation super clean and simple. Work primarily with builtins but easily extend. Provide a nice API for usage (hence returning false instead of a truthy empty array for the return value of validate).

    example usage

    var validate = require('validate-params-schema')
    functon sum(params, callback) {
      // define our assumed params
      var errors = validate(params, {
        x: {required:true, type:Number},
        y: {required:true, type:Number}
      // err first!
      if (errors) {
      else {
        callback(null, params.x + params.y)


    validate(params, schema)

    • params a plain old javascript object that we assume came from JSON
    • schema a plain javascript object for describing the shape of the data

    schema keys

    • required either true or false (or leave it out completely)
    • type can be one of Object, String, Number, Array and Boolean
    • min any Number (or anything allowed by a custom type)
    • max any Number (or anything allowed by a custom type)

    Check out ./examples for more on custom types and ranges (and the tests).


    npm i validate-params-schema

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    • brianleroux