Ajv Examples You Can Edit and Run

5 small Ajv examples written by AgentGid from the official docs, one feature each. Every one runs in your browser: change the code and see the result at once, or describe a change and let AI rewrite it. The screenshots are taken from the same code by our server, which also checks that each example starts without errors.

Ajv: usage and stats 151 AI-built projects use it

Compiling a schema with Ajv: screenshot of the example running

Compiling a schema with AjvAdd a sample such as { foo: "7" } or make bar required and watch which lines turn invalid.

Collecting all errors with Ajv: screenshot of the example running

Collecting all errors with AjvFix one field in data at a time and watch the allErrors list shrink while the default count stays at one until everything passes.

One-call validation with ajv.validate: screenshot of the example running

One-call validation with ajv.validateRemove the saved.push line and print ajv.errors after the loop to see that only the last result is left.

Reusing schemas with addSchema and $ref: screenshot of the example running

Reusing schemas with addSchema and $refChange the zip pattern in the address schema once and both home and work addresses follow it.

Custom formats in Ajv: screenshot of the example running

Custom formats in AjvChange a channel to 300 or a name to start with a digit to see the format error for that field.

Try them all in one place

import Ajv from "ajv"

const ajv = new Ajv()

const schema = {
  type: "object",
  properties: {
    foo: { type: "integer" },
    bar: { type: "string" },
  },
  required: ["foo"],
  additionalProperties: false,
}

// compile once, then reuse the function for every object
const validate = ajv.compile(schema)

const samples = [
  { foo: 1, bar: "abc" },
  { foo: 42 },
  { bar: "abc" },
  { foo: 1.5 },
  { foo: 2, bar: 7 },
  { foo: 3, extra: true },
]

for (const data of samples) {
  const valid = validate(data)
  console.log(JSON.stringify(data).padEnd(22), valid ? "valid" : "invalid")
  if (!valid) console.log("   ", ajv.errorsText(validate.errors))
}

Ctrl/⌘ + Enter runs

Add a sample such as { foo: "7" } or make bar required and watch which lines turn invalid. Code written by AgentGid [1]. How it works, with a screenshot →

Checked Oct 12, 2026: each example starts without errors in Chromium with ajv 8.20.0. Needs WebGL.

Sources

Explanations written by AgentGid from the official docs; the numbers in brackets point here. The code marked "written by AgentGid" is ours and free to copy.

Building something with Ajv? Ask AgentGid →