let name: string = "bob"; doesn't work.

[harukaeru]

Hello, I start to use TypeScript recently. It's super useful language for me :)
By the way, I'm in a tutorial about String Type in here https://www.typescriptlang.org/docs/handbook/basic-types.html

TypeScript Version:

1.8.10

Code

It doesn't work.

hello.ts

let name: string = "bob";

Whenever I compile, the compiler will emit the following.

$ tsc hello.ts
../../usr/local/lib/node_modules/typescript/lib/lib.d.ts(16757,13): error TS2451: Cannot redeclare block-scoped variable 'name'.
hello.ts(1,5): error TS2451: Cannot redeclare block-scoped variable 'name'.

It works.

hello.ts

let aname: string = "bob";

Expecting Behavior

I read a part of the lib.d.ts and it has declare var name: string;. So I may understand the compiler emits an error. However what concept cannot we use the variable name in TypeScript?
And I think the tutorial which doesn't work is not good :(
Or is there something is wrong with me? I hope to replay an answer :)

[basarat]

Because there is already a variable called name on the global scope. Try it out in your browser, console.log(name) and you will see an empty string (or maybe some other string) instead of undefined.

Fix

Put your name variable in a module or namespace : https://basarat.gitbooks.io/typescript/content/docs/project/modules.html

[basarat]

Documentation for this variable : https://developer.mozilla.org/en-US/docs/Web/API/Window/name 🌹

[harukaeru]

@basarat
Thank you for your answer. That has such a meaning...
I didn't know there is already name variable in global scope :)

@DanielRosenwasser
Thank you for fixing the document, too :)