TypeTags .assign

Overview

The .assign method allows us assign the well-known Symbol.toStringTag property to an object. If it receives an object withtout a toString method defined, it will assign Object.prototype.toString to it prior to the received tag string-value.

Usage

TypeTags.assign(object, tag)
  • Assign or alter the Symbol.toStringTag property of an object.
import { TypeTags } from 'typetags'


const proto = {}
const tag = 'CustomTag'


TypeTags.assign(proto, tag)


TypeTags.get(proto)
// → [object CustomTag]


proto[Symbol.toStringTag]
// → 'CustomTag'

If object doesn't have a toString method defined, assign will add Object.prototype.toString to the object prior to its tag value.

We can use the has method to check if toString has already been defined.

import { TypeTags } from 'typetags'


const user = Object.create(null) // null prototype


TypeTags.get(user)
// → undefined


if (!TypeTags.has(user)) {
  TypeTags.assign(user, 'User')
}


TypeTags.get(user)
// → '[object User]'


user[Symbol.toStringTag]
// → 'User'

Signature

assign<T>(object: T, tag: string): T