@gimmi/es5-validator

Use in browser

<script src="src/validator.js"></script>
<script type="text/javascript">
    new Validator({ str: 123 }).checkKey('str', Number)
</script>

Also see In browser spec runner

Use in NodeJS

const Validator = require('es5-validator')

new Validator({ str: 123 }).checkKey('str', Number)

Also see nodejs test by running npm test