problem with interfaces

[mhegazy]

From @jeevan-reddy on December 20, 2015 16:56

Error:
Argument of type '{ size: number; label: string; }' is not assignable to parameter of type '{ label: string; }'.
Object literal may only specify known properties, and 'size' does not exist in type '{ label: string; }'.

My typesscript version is 1.7.5

Steps to recreate the Error:

1. Create a .ts file named script.ts
2. type the following code :

function printLabel(labelledObj: {label: string}) {
  console.log(labelledObj.label);
}
var myObj = {size: 10, label: "Size 10 Object"};  // myObj is of type {size:number;label:string}
// printLabel(myObj);
printLabel({size: 10, label: "Size 10 Object"});   // the object being passed to printLabel is also of type {size:number;label:string}

3. Compile the script.ts using command tsc script either from command prompt/powershell

it is clearly mentioned in documentation that if we send extra arguments it is ok .please refer to attached code-snippet

But what is the difference if i assign an object to a variable , pass that variable as argument and if i directly pass the object as argument ?

Copied from original issue: microsoft/TypeScript#6175

[mhegazy]

From @kitsonk on December 20, 2015 17:49

The handbook is currently wrong as of TypeScript 1.6.3. It was discussed in #3755 and was changed in #3823.

IIRC, the team are in the process of doing a whole update of the handbook, because there are a few other issues with it.

[mhegazy]

From @DanielRosenwasser on December 20, 2015 20:47

Thanks for catching this @jeevan-reddy, I'll be amending this in #64

[DanielRosenwasser]

Duplicate of #64.

[madroneropaulo]

Could you please at least add a warning message in the handbook like "Some of this information may be outdated"? I mean, I lost some time trying to figure out whats wrong with my code while following this handbook for learning typescript. A version warning message would be enough for considering the problem as a version incongruity.