nodejs中的Static变量

Question

I am using ES6 style code within NodeJS.

When trying to create a static variable I get an error.

Code:

'use strict';

module.exports =  class Count {
    static addToCounter() {
        //this.count = this.count + 1 || 1;
        this.count = this.count + 1;
        console.log(`count: `+this.count);
    }
    static count = "";
}

Error:

static count = "";
                 ^

SyntaxError: Unexpected token =
    at new Script (vm.js:74:7)
    at createScript (vm.js:246:10)
    at Object.runInThisContext (vm.js:298:10)
    at Module._compile (internal/modules/cjs/loader.js:646:28)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:689:10)
    at Module.load (internal/modules/cjs/loader.js:589:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:528:12)
    at Function.Module._load (internal/modules/cjs/loader.js:520:3)
    at Module.require (internal/modules/cjs/loader.js:626:17)
    at require (internal/modules/cjs/helpers.js:20:18)

What is my mistake?

Answer 1

This proposal is still in stage-2. As of now, without the babel plugin transform-class-properties , it is not possible to use the assignment operator along with the static keyword.

Answer 2

If you are not transpiling, you will need to be using at least Node.js v12.4.0 for static class fields. https://node.green/#ESNEXT-candidate--stage-3--static-class-fields-public-static-class-fields shows supported features across Node.js versions.

Also, inside your addToCounter function, you would also need to use Count.count = Count.count + 1 . If you want to be able to store properties on each instance, then you would need to remove the static keywords before both the method and the property declaration.