JSDoc: assign type to inline variable

Question

Can I assign a type to a variable which gets a object result from a third party library?

const result = thirdPartyLib.doSomething();

Now I may have a ES6 class

class MyClass {
  ...
}

And I want to annotate my result to be of type MyClass.

Is this possible using JSDoc?

Answer 1

The JSDoc @type {…} tag can be applied to a local variable to declare its type.

/** @type {MyClass} */
const result = thirdPartyLib.doSomething();

However, instead of adding this declaration everywhere you call the function, you could use the @external tag to add JSDoc types to thirdPartyLib.doSomething(), allowing the local variable types to be inferred correctly.

/**
 * @external thirdPartyLib
 */
/**
 * @function external:thirdPartyLib.doSomething
 * @returns {MyClass}
 */

const result = thirdPartyLib.doSomething();