Small example of using Ajv and JSONSchema to validate JSON model.

main.js

// Common schema.
const defSchema = {
  $id: "http://my-domain.com/schemas/defs.json",
  definitions: {
    URL: {
      type: "string",
      format: "uri",
      pattern: "^(https?|wss?|ftp)://"
    }
  }
};

// Each model schema.
const campaignSchema = {
  $id: "http://my-domain.com/schemas/campaign-schema.json",
  title: "Campaign",
  description: "",
  type: "object",
  required: ['title'],
  properties: {
    title: {
      type: "string"
    },
    backgroundImageURL: {
      $ref: "defs.json#/definitions/URL"
    }
  }
}

var ajv = new Ajv();
var campaignValidator = ajv.addSchema(defSchema).compile(campaignSchema);

const campaign = {
  backgroundImageURL: "https://www.google.com"
}

var valid = campaignValidator(campaign);

// Using the AJV directly we can use "errorsText()"
// Otherwhise, we have to get errors from the validator
// Copy errors or it will be overwritten on next run.
// var valid = ajv.addSchema(campaignSchema, 'campaignSchema').validate('campaignSchema', campaign);

console.log({ valid });

if (!valid) {
  const { errors } = campaignValidator;
  // const errors = ajv.errorsText();
  console.log({ errors });
}