Access the feasibility of converting typescript classes into JS classes?

[henites72]

In issue #2, we decided to use Javascript as a programming language for our system. But we implement all the abstractions in the system using Typescript, so we want to show a converted abstraction, completely written in Javascript?

[mezzzi]

@henites72 can you post here an example typescript class, a small one, if possible?

[henites72]

@mezzzi should it be from the abstractions or some sample OOP code in Typescript?

[mezzzi]

I have found this class from @henites72's repository (book-projects). We can show the feasibility using this as a sample typescript class.

class SymbolTable {
  public table: Object;

  constructor() {
    this.intilalizeSymbolTable();
  }

  intilalizeSymbolTable() {
    this.table = {
      SP: 0,
      LCL: 1,
      ARG: 2,
      THIS: 3,
      THAT: 4,
      R0: 0,
      R1: 1,
      SCREEN: 16384,
      KBD: 24576
    };
  }

  addEntry(symbol: string, address: number) {
    this.table[symbol] = address;
  }

  contains(symbol: string): boolean {
    return this.table.hasOwnProperty(symbol);
  }

  getAddress(symbol: string): number {
    if (this.contains(symbol)) return this.table[symbol];
  }
}

export default SymbolTable;

The full code is available here: https://github.com/nandtotetris/henok-book-projects/blob/master/projects/06/src/symboltable.ts

[henites72]

Great @mezzzi!

[Buranch]

I'm experimenting with this tool https://www.typescriptlang.org/play/ looks promising so far.

[mikerezene]

So are we going to write the whole code in Javascript and then we are going to find a tool to convert it to Typescript? is that what you meant?

[mezzzi]

No @mikereze, it is the other way around.

[mezzzi]

The sample typescript code posted above can be converted into the following javascript equivalent:

class SymbolTable {
    constructor() {
        this.intilalizeSymbolTable();
    }
    intilalizeSymbolTable() {
        this.table = {
            SP: 0,
            LCL: 1,
            ARG: 2,
            THIS: 3,
            THAT: 4,
            R0: 0,
            R1: 1,
            R2: 2,
            R3: 3,
            R4: 4,
            R5: 5,
            R6: 6,
            R7: 7,
            R8: 8,
            R9: 9,
            R10: 10,
            R11: 11,
            R12: 12,
            R13: 13,
            R14: 14,
            R15: 15,
            SCREEN: 16384,
            KBD: 24576
        };
    }
    addEntry(symbol, address) {
        this.table[symbol] = address;
    }
    contains(symbol) {
        return this.table.hasOwnProperty(symbol);
    }
    getAddress(symbol) {
        if (this.contains(symbol))
            return this.table[symbol];
    }
}
export default SymbolTable;

There is this tool that can help with the conversion: https://www.typescriptlang.org/play/index.html. Thanks @Buranch for suggesting it. But we shouldn't rely entirely on the tool. We need to double check each converted code to make sure there isn't error in the conversion.

[Buranch]

@mezzi yes I've already suggested a human review back in our slack discussion

On Friday, February 28, 2020, mezzzi notifications@github.com wrote:

The sample typescript code posted above can be converted into the following javascript equivalent:

class SymbolTable { constructor() { this.intilalizeSymbolTable(); } intilalizeSymbolTable() { this.table = { SP: 0, LCL: 1, ARG: 2, THIS: 3, THAT: 4, R0: 0, R1: 1, R2: 2, R3: 3, R4: 4, R5: 5, R6: 6, R7: 7, R8: 8, R9: 9, R10: 10, R11: 11, R12: 12, R13: 13, R14: 14, R15: 15, SCREEN: 16384, KBD: 24576 }; } addEntry(symbol, address) { this.table[symbol] = address; } contains(symbol) { return this.table.hasOwnProperty(symbol); } getAddress(symbol) { if (this.contains(symbol)) return this.table[symbol]; } } export default SymbolTable;

There is this tool that can help with the conversion: https://www.typescriptlang.org/play/index.html. Thanks @Buranch https://github.com/Buranch for suggesting it. But we shouldn't rely entirely on the tool. We need to double check each converted code to make sure there isn't error in the conversion.

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[mezzzi]

This article (https://medium.com/javascript-scene/the-typescript-tax-132ff4cb175b) provides a detailed comparison, pro and con analysis, between js and typescript. And the author updates the scores to reflect latest developments in each ecosystem. As of now, the scores favors js . So that kind of puts us in the right track, at least thinking of long term benefits to be gained, as the project matures and scales.