Typescript allows to create a class field name by starting with number

Question

Why typescript allows class field name in number

 1: number = 1;
 2: number = 2;

As per this discussion Why can't variable names start with numbers? We can't create a class field name starting with number(even JavaScript also does not allow, if we define a variable name is starting with number). But in typescript we can create a class field name starting with number(whatever). Why? and it's a bug in typescript?.

Reference

it doesn't, I'm not sure how you get that working? in the playground at least it doesn't https://www.typescriptlang.org/play/index.html#src=let%201%3Anumber%20%3D%201%3B — toskv, Aug 03 '17 at 10:34
It does not accept inside the method. Am asking about when you declare the variable globally. — Ramesh Rajendran, Aug 03 '17 at 10:37
Even then it does not work. Provide a complete verifiable example. — Murat Karagöz, Aug 03 '17 at 10:38
@toskv and Murat I have attached the reference. Could you please explain for the down vote. — Ramesh Rajendran, Aug 03 '17 at 10:40
I am not understanding with variable name and class filed name in typescript :( . HMM! — Ramesh Rajendran, Aug 03 '17 at 10:42

cyr_x · Accepted Answer · 2017-08-03T10:47:56.793

7

Those definitions of 1 and 2 aren't variable definitions, you're defining class members, which is totally fine to name them by a number.

But remember you can't access them by this.1 you have to use this[1].

In Javascript object properties can be named by a number (which is for example what the implementation of Array is doing), because (as @zerkms statet in the comments) they're implicitly converted into strings.

edited Aug 03 '17 at 10:47

answered Aug 03 '17 at 10:43

cyr_x

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For more reading material https://stackoverflow.com/questions/4968406/javascript-property-access-dot-notation-vs-brackets – Murat Karagöz Aug 03 '17 at 10:45
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"In Javascript object properties can be named by a number" --- JS object properties are strings. They are implicitly converted. – zerkms Aug 03 '17 at 10:45
But I don't know why they are voting down for this question – Ramesh Rajendran Aug 03 '17 at 10:45
@zerkms you're correct they're converted to strings. Added it to my answer. – cyr_x Aug 03 '17 at 10:46
@cyrix class member means method also a class member. but why method does not accept it.? – Ramesh Rajendran Aug 03 '17 at 10:50
You can also use a number for a class method name: `1() { return 2; }`, typescript won't complain about it. – cyr_x Aug 03 '17 at 10:52
But I can't use it dude – Ramesh Rajendran Aug 03 '17 at 10:57
Sure you can with `this[1]()`. But anyways don't name your class members and object properties by a `number` it's bad practise, unless you have a really really good reason to do so. – cyr_x Aug 03 '17 at 10:59

Typescript allows to create a class field name by starting with number

Reference

1 Answers1