Prototype of typescript webpack loader

gistfile1.js

var typescript = require('typescript')
var path = require('path')

var compilerOptions = {
    target: typescript.ScriptTarget.ES5
}
var files = {};

var servicesHost = {
    getScriptFileNames: function () { return Object.keys(files) },
    getScriptVersion: function (filename) { return files[filename] && files[filename].version.toString() },
    getScriptSnapshot: function (filename) {
        var file = files[filename];
        return {
            getText: function (start, end) { return file.text.substring(start, end) },
            getLength: function () { return file.text.length },
            getLineStartPositions: function () { return [] },
            getChangeRange: function (oldSnapshot) { return undefined }
        };
    },
    getCurrentDirectory: function () { return process.cwd() },
    getScriptIsOpen: function () { return true },
    getCompilationSettings: function () { return compilerOptions },
    getDefaultLibFilename: function (options) { return 'lib.d.ts' },
    log: function (message) { console.log(message) }
};
var langService = typescript.createLanguageService(servicesHost, typescript.createDocumentRegistry())

module.exports = function (content) {
    var filePath = path.normalize(this.resourcePath);
    
    if (!Object.prototype.hasOwnProperty.call(files, filePath)) {
        var program = typescript.createProgram([filePath], compilerOptions, typescript.createCompilerHost(compilerOptions));

        program.getSourceFiles().forEach(function (file) {
            files[path.normalize(file.filename)] = { version: 0, text: file.text };
        })
    }

    var file = files[filePath];
    file.text = content;
    file.version++;

    var output = langService.getEmitOutput(filePath);

    var diagnostics = langService.getCompilerOptionsDiagnostics()
                    .concat(langService.getSyntacticDiagnostics(filePath))
                    .concat(langService.getSemanticDiagnostics(filePath));

    diagnostics.forEach(function(diagnostic) {
        var lineChar = diagnostic.file.getLineAndCharacterFromPosition(diagnostic.start);
        this.emitError('  ' +diagnostic.file && diagnostic.file.filename + ' (' + lineChar.line + ', ' + lineChar.character + '): ' + diagnostic.messageText)
    }.bind(this));

    if (output.outputFiles.length == 0) return '';

    return output.outputFiles[0].text;
}