Ignore __proto__

[Riim]

TypeScript Version: 2.2.0

Code:

{ __proto__: {} } as { [key: string]: string }

Expected behavior:
Ok

Actual behavior:
Type '{ __proto__: {}; }' cannot be converted to type '{ [key: string]: string; }'.

[felixfbecker]

This is extremely annoying. Consider this

export const stepComponent = {
    bindings: {
        hasNextStep: '>',
        hasPreviousStep: '>',
        onNextStep: '&',
        onPreviousStep: '&'
    },
    controller: class StepController {
        public hasNextStep: boolean;
        public hasPreviousStep: boolean;
        public onNextStep: Function;
        public onPreviousStep: Function;
    }
};

angular.component('credentialsStep', {
    __proto__: stepComponent,
    bindings: {
        __proto__: stepComponent.bindings,
        user: '>'
    },
    controller: class CredentialsStepController extends stepComponent.controller {

        public credentialsForm: angular.IFormController;
        public user: any;
        public repeatedPassword: string;
    }
});

The credentialsComponent should be valid and have all properties of the stepComponent, instead it fails with

[ts]
Argument of type '{ __proto__: { bindings: { hasNextStep: string; hasPreviousStep: string; onNextStep: string; onPr...' is not assignable to parameter of type 'IComponentOptions'.
  Object literal may only specify known properties, and '__proto__' does not exist in type 'IComponentOptions'.

[jolexxa]

Also ran into this tonight while making custom error subclasses for Node. Was expecting TypeScript to ignore anything relating to .__proto__ or at least have a mechanism for avoiding it.

class CustomError extends Error {
	constructor (message?: string) {
		// 'Error' breaks prototype chain here
		super(message);

		// restore prototype chain
		const actualProto = new.target.prototype;

		if (Object.setPrototypeOf) { Object.setPrototypeOf(this, actualProto); } else { this.__proto__ = actualProto; }
	}
}

Credits:
https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-2.html#support-for-newtarget

https://stackoverflow.com/a/48342359

[exedor]

Same here. I just ran into this using the following loop structure:

for (let i in qList) { qList[i].prop1.trim(); qList[i].prop2.trim(); }

It is a simple array of objects. The job of the loop is to iterate over all the objects and trim two of it's string properties. The documentation for typescript talks about iterating over the indexes of the array. The problem is after it's done doing that, the value of i changes from an index to 'contains' which is method on

__proto__

This is completely broke our application when we upgraded typescript to 2.9.2. It worked great on 1.8.

[mike-marcacci]

Just as a note, a full solution for this is described in this RFC: #38385.