试图通过preventExcessPropertyErrors编译器选项抑制TS2339

Question

Here is the code:

var x = {};
x.test = 'abc';

Getting typescript compiler error:

TS2339: Property 'test' does not exist on type '{}'.

I want to suppress this warning for object literals, I suppose that putting suppressExcessPropertyErrors into tsconfig.json should solve this.

tsconfig:

{
    "compilerOptions": {
        "suppressExcessPropertyErrors": true
    },
    ...
}

But nothing changed.. compiler still showing the error.

Thank you for any hints ;)

Answer 1

I suppose that putting suppressExcessPropertyErrors into tsconfig.json should solve this.

No. It suppresses excess properties in object construction eg

var x = {};
x = {test:'abc'};

I want to suppress this warning for object literals

You can do anything you want using the any type eg

var x:any = {};
x.test = 'abc';

More

This is called lazy object initiliazation and patterns for dealing with it are covered here : https://basarat.gitbooks.io/typescript/content/docs/tips/lazyObjectLiteralInitialization.html

Answer 2

I could agree with @basarat by some points, but please let me to add some suggestions also.

Declaration object props like this could a make sense by several reasons:

var x = {
  test: ''
};
x.test = 'abc';

1. You will get intellisense support and in next time when you will call x object you will see which properties this object contains.
2. Good for testing. You will be sure that construction of your object will not be changed somewhere in your project and can write tests keep in mind it.
3. You will avoid to overriding your object properties with new ones. It could be if you declare you object as any type.

Explanation :

// origin object x with originProp property
var x: any = {
  originProp: 'abc'
};
// new object with new newProp property
x = {
  newProp:'abc'
};