gistfile1.js

var revalidator = require('revalidator')

var obj = {
  title: 'Abe',
  value: '10'
}

var schema = {
  properties: {
    title: {
      type: 'string'
    },
    value: {
      type: 'number'
    }
  }
}

console.dir(revalidator.validate(obj, schema, {cast: true})) // true

obj.value = 10

console.dir(revalidator.validate(obj, schema, {cast: true})) // true

schema.properties.value.type = ['number']

console.dir(revalidator.validate(obj, schema, {cast: true})) // true

obj.value = '10'

console.dir(revalidator.validate(obj, schema, {cast: true})) // false