operator-overload.js adds overloading to javascript. It can be written in a simple notation and can be converted by the built-in transpiler to work in vanilla javascript.

Note: This text was translated using the DeepL translation. The translation may not be perfect.

$ npm install --save operator-overloadjs

"scripts": {
    "build": "overload -d ./src -o ./dist", // To transpile the entire directory
    "transpile": "overload" // To transpile a single file
},
"type": "module"

In this example, the '+' operator of the customArray class is overloaded to allow easier string concatenation than using the concat method.

import _overload from "operator-overloadjs";
class CustomArray extends Array {
    [_overload.plus](a) {
        return this.concat(a);
    }
}
const array_a = new CustomArray();
const array_b = new CustomArray();
array_b.push(1, 1, 3);
array_a.push('a', 'b', 'c');
console.log(array_a + array_b);

Transpile the source code.

$ npm run build

Alternatively, you can specify the file name directly to transpile it.

$ npm run transpile -- ./src/customArray.js -o ./dist/customArray.js

The transpiled file will be output.

import _overload from "operator-overloadjs";
class CustomArray extends Array {
    [_overload.plus](a) {
        return this.concat(a);
    }
}
const array_a = new CustomArray();
const array_b = new CustomArray();
array_b.push(1, 1, 3);
array_a.push('a', 'b', 'c');
- console.log(array_a + array_b);
+ console.log((array_a)[_overload.plus](array_b));

Let's run it.

$ node ./dist/customArray.js
CustomArray(6) [ 'a', 'b', 'c', 1, 1, 3 ]

It worked.

Note: In this example, we have overloaded the customArray class we created, not the Array class. Therefore, if you want to overload the Array class, write the following

Object.defineProperty(Array.prototype, _overload.plus, {
   value: function(a) {
       return this.concat(a);
   }
});

The following is a list of operators that can be overloaded as in the previous example.

Note: 'this' refers to 'a' and the first argument refers to 'b'.

operator-overload.js may contain a number of bugs. If you find a bug, please contact us in Issues.