Develop Reference

Typescript allows to save wrong types. why?

I'm using Typescript in NodeJS. I defined an interface and I passed it to the variable. But when I send some data that is not match with interface type for example I pass number instead of string for text property that I created in interface, Typescirpt still can save them in the variable. In react.js I had the same issue.
Code is very simple, and I'm using the memory of nodejs to make that typescript works fine:
models-types file:
export interface Todo {
id: string;
text: string;
}
Controller file:
import { RequestHandler } from "express";
import { Todo } from "../models/todo";
const data: Todo[] = [];
export const todoPostHandler: RequestHandler = (req, res, next) => {
try {
const text = (req.body as { text: string }).text;
if (!text) {
throw { message: "invalid text" };
}
const incomingData = { id: Math.random().toString(), text };
data.push(incomingData);
res.status(201).json({ message: "data created in the server", data: incomingData });
} catch (error) {
return next(error);
}
};
Json file:
{
"compilerOptions": {
/* Visit https://aka.ms/tsconfig.json to read more about this file */
/* Basic Options */
// "incremental": true, /* Enable incremental compilation */
"target": "es2018" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */,
"module": "commonjs",
"moduleResolution": "node" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */,
// "lib": [], /* Specify library files to be included in the compilation. */
// "allowJs": true, /* Allow javascript files to be compiled. */
// "checkJs": true, /* Report errors in .js files. */
// "jsx": "preserve", /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
// "declaration": true, /* Generates corresponding '.d.ts' file. */
// "declarationMap": true, /* Generates a sourcemap for each corresponding '.d.ts' file. */
// "sourceMap": true, /* Generates corresponding '.map' file. */
// "outFile": "./", /* Concatenate and emit output to single file. */
"outDir": "./dist" /* Redirect output structure to the directory. */,
"rootDir": "./src" /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */,
// "composite": true, /* Enable project compilation */
// "tsBuildInfoFile": "./", /* Specify file to store incremental compilation information */
// "removeComments": true, /* Do not emit comments to output. */
// "noEmit": true, /* Do not emit outputs. */
// "importHelpers": true, /* Import emit helpers from 'tslib'. */
// "downlevelIteration": true, /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
// "isolatedModules": true, /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
/* Strict Type-Checking Options */
"strict": true /* Enable all strict type-checking options. */,
// "noImplicitAny": true, /* Raise error on expressions and declarations with an implied 'any' type. */
// "strictNullChecks": true, /* Enable strict null checks. */
// "strictFunctionTypes": true, /* Enable strict checking of function types. */
// "strictBindCallApply": true, /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
// "strictPropertyInitialization": true, /* Enable strict checking of property initialization in classes. */
// "noImplicitThis": true, /* Raise error on 'this' expressions with an implied 'any' type. */
// "alwaysStrict": true, /* Parse in strict mode and emit "use strict" for each source file. */
/* Additional Checks */
// "noUnusedLocals": true, /* Report errors on unused locals. */
// "noUnusedParameters": true, /* Report errors on unused parameters. */
// "noImplicitReturns": true, /* Report error when not all code paths in function return a value. */
// "noFallthroughCasesInSwitch": true, /* Report errors for fallthrough cases in switch statement. */
// "noUncheckedIndexedAccess": true, /* Include 'undefined' in index signature results */
/* Module Resolution Options */
// "moduleResolution": "node", /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
// "baseUrl": "./", /* Base directory to resolve non-absolute module names. */
// "paths": {}, /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
// "rootDirs": [], /* List of root folders whose combined content represents the structure of the project at runtime. */
// "typeRoots": [], /* List of folders to include type definitions from. */
// "types": [], /* Type declaration files to be included in compilation. */
// "allowSyntheticDefaultImports": true, /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
"esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */,
// "preserveSymlinks": true, /* Do not resolve the real path of symlinks. */
// "allowUmdGlobalAccess": true, /* Allow accessing UMD globals from modules. */
/* Source Map Options */
// "sourceRoot": "", /* Specify the location where debugger should locate TypeScript files instead of source locations. */
// "mapRoot": "", /* Specify the location where debugger should locate map files instead of generated locations. */
// "inlineSourceMap": true, /* Emit a single file with source maps instead of having a separate file. */
// "inlineSources": true, /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
/* Experimental Options */
// "experimentalDecorators": true, /* Enables experimental support for ES7 decorators. */
// "emitDecoratorMetadata": true, /* Enables experimental support for emitting type metadata for decorators. */
/* Advanced Options */
"skipLibCheck": true /* Skip type checking of declaration files. */,
"forceConsistentCasingInFileNames": true /* Disallow inconsistently-cased references to the same file. */
}
}

TypeScript doesn't check any types at runtime.
If you use X as Y you basically pinky-swear that the data X is of the type Y and TypeScript will believe you.
If you don't want to do that, you'll need a "codec" at the "edge" of the TypeScript world that will choke on data that is actually invalid; Zod is a fairly popular TypeScript-native choice to deserialize and schema-validate data. Other choices include e.g. io-ts.

How to Call Typescript Function From Index.html?

I've got an input element which tries calling a typescript function during the onchange event. However it doesn't work and I get the following error: inputChange is not defined.
In my main.ts file, I've got a simple function called inputChange which just console logs "Hello World!".
// index.html
<input onchange="inputChange()"/>
// main.ts
function inputChange(){
console.log('Hello World!')
}
Does anyone know how I can access functions like inputChange from my index.html file? (Also everything else in my main.ts file works as normal but for some reason I can't access typescript functions/variables from index.html)
I'm using webpack and babel to compile the typescript file into a bundle.js which is then appended into my index.html file by HTMLWebpackPlugin.
This is my tsconfig file:
{
"compilerOptions": {
/* Basic Options */
"target": "es5", /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */
"module": "commonjs", /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
"lib": ["es6","dom"], /* Specify library files to be included in the compilation. */
"allowJs": false, /* Allow javascript files to be compiled. */
"sourceMap": true, /* Generates corresponding '.map' file. */
/* Strict Type-Checking Options */
"strict": true, /* Enable all strict type-checking options. */
"noImplicitAny": true, /* Raise error on expressions and declarations with an implied 'any' type. */
"strictNullChecks": true, /* Enable strict null checks. */
"strictFunctionTypes": true, /* Enable strict checking of function types. */
"strictBindCallApply": true, /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
"strictPropertyInitialization": true, /* Enable strict checking of property initialization in classes. */
"noImplicitThis": true, /* Raise error on 'this' expressions with an implied 'any' type. */
"alwaysStrict": true, /* Parse in strict mode and emit "use strict" for each source file. */
/* Additional Checks */
"noUnusedLocals": false, /* annoying when just testing */ // "noUnusedLocals": false, /* Report errors on unused locals. */
"noUnusedParameters": false, /* annoying when just testing */ // "noUnusedParameters": true, /* Report errors on unused parameters. */
"noImplicitReturns": true, /* Report error when not all code paths in function return a value. */
"noFallthroughCasesInSwitch": true, /* Report errors for fallthrough cases in switch statement. */
/* Module Resolution Options */
"allowSyntheticDefaultImports": true, /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
"esModuleInterop": true, /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
/* Advanced Options */
"skipLibCheck": true, /* Skip type checking of declaration files. */
"forceConsistentCasingInFileNames": true /* Disallow inconsistently-cased references to the same file. */
},
"compileOnSave": true,
"exclude": ["node_modules"],
"include": ["./public"]
}

This is one of the many reasons not to use onxyz-attribute-style event handlers: They require that the function you use has to be a global. It sounds like you have TypeScript set up to use modules, so top-level declarations in TypeScript files aren't globals.
Instead, hook up the handler to the input using JavaScript, identifying the input via where it is in the DOM, its class, or its ID. For instance, here's an example using an ID:
<input id="the-input">
and in your TypeScript code in the module where inputChange is defined (or another module that imports it):
document.getElementById("the-input").addEventListener("change", inputChange);

Create Readable JS from Typescript

I want my compiled JS code to be readable (similar as if I had written it), so it's easier to debug but the typescript compiler makes several changes which I'm hoping I can turn off.
For example:
When I compile my typescript it changes all the import names eg.
import AWS from 'aws-sdk' => const aws_sdk_1 = __importDefault(require("aws-sdk"));
rather than const aws-sdk = require('aws-sdk')
Additionally, it removed all line spacing, which I included to make it more readable and break it up.
Is there any way to change these settings?
tsconfig.json
{
"compilerOptions": {
/* Basic Options */
// "incremental": true, /* Enable incremental compilation */
"target": "es2017",
/* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019' or 'ESNEXT'. */
"module": "commonjs",
/* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
// "lib": [], /* Specify library files to be included in the compilation. */
"allowJs": true,
/* Allow javascript files to be compiled. */
"checkJs": true,
/* Report errors in .js files. */
// "jsx": "preserve", /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
// "declaration": true, /* Generates corresponding '.d.ts' file. */
// "declarationMap": true, /* Generates a sourcemap for each corresponding '.d.ts' file. */
// "sourceMap": true, /* Generates corresponding '.map' file. */
// "outFile": "./", /* Concatenate and emit output to single file. */
"outDir": "./dist",
/* Redirect output structure to the directory. */
// "rootDir": "./", /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
// "composite": true, /* Enable project compilation */
// "tsBuildInfoFile": "./", /* Specify file to store incremental compilation information */
// "removeComments": true, /* Do not emit comments to output. */
// "noEmit": true, /* Do not emit outputs. */
// "importHelpers": true, /* Import emit helpers from 'tslib'. */
// "downlevelIteration": true, /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
// "isolatedModules": true, /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
/* Strict Type-Checking Options */
"strict": true,
/* Enable all strict type-checking options. */
// "noImplicitAny": true, /* Raise error on expressions and declarations with an implied 'any' type. */
// "strictNullChecks": true, /* Enable strict null checks. */
// "strictFunctionTypes": true, /* Enable strict checking of function types. */
// "strictBindCallApply": true, /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
// "strictPropertyInitialization": true, /* Enable strict checking of property initialization in classes. */
// "noImplicitThis": true, /* Raise error on 'this' expressions with an implied 'any' type. */
// "alwaysStrict": false, /* Parse in strict mode and emit "use strict" for each source file. */
/* Additional Checks */
// "noUnusedLocals": true, /* Report errors on unused locals. */
// "noUnusedParameters": true, /* Report errors on unused parameters. */
// "noImplicitReturns": true, /* Report error when not all code paths in function return a value. */
// "noFallthroughCasesInSwitch": true, /* Report errors for fallthrough cases in switch statement. */
/* Module Resolution Options */
"moduleResolution": "node",
/* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
// "baseUrl": "./", /* Base directory to resolve non-absolute module names. */
// "paths": {}, /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
// "rootDirs": [], /* List of root folders whose combined content represents the structure of the project at runtime. */
// "typeRoots": [], /* List of folders to include type definitions from. */
// "types": [], /* Type declaration files to be included in compilation. */
// "allowSyntheticDefaultImports": true, /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
"esModuleInterop": true,
/* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
// "preserveSymlinks": true, /* Do not resolve the real path of symlinks. */
"allowUmdGlobalAccess": true,
/* Allow accessing UMD globals from modules. */
/* Source Map Options */
// "sourceRoot": "", /* Specify the location where debugger should locate TypeScript files instead of source locations. */
// "mapRoot": "", /* Specify the location where debugger should locate map files instead of generated locations. */
// "inlineSourceMap": true, /* Emit a single file with source maps instead of having a separate file. */
// "inlineSources": true, /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
/* Experimental Options */
"experimentalDecorators": true,
/* Enables experimental support for ES7 decorators. */
// "emitDecoratorMetadata": true, /* Enables experimental support for emitting type metadata for decorators. */
}
}

If the problem in debugging is the only reason you want readable JS. Then you can debug your ts file (readable) in chrome using this command
node --inspect -r ts-node/register <your-ts-file.ts>
For the above command, you will first have to install ts-node.
npm install --save ts-node

You cannot preserve whitespace. The processing required by TS compiler, which is dependent on the tsconfig settings, and could dramatically change the output, does not allow for trying to keep any formatting intact.
The target and module system you have will change the output JS, especially imports. TS will try to handle all the scenarios, even if you wouldn't normally.
You can turn off the __importDefault helper functions however by using
esModuleInterop: false
You should treat the generated js as a binary. It is a built output, and you shouldn't care about it's format. You wouldn't look inside a DLL and care what it looked like. The only time you will ever need to care would be if you were moving away from TS, and if that were the case, processing the files to simply remove the TS annotations would be more easy than trying to make the transpiled source look exactly like you want it.
For debugging, source maps are critical. Output them, and debug your TS, not the generated JS.

Protractor Typescript Problem converting ts to js file in tsConfig file. How do I fix this?

I tried to convert the ts to a js file in I thought I had set up the tsconfig file correct correctly.
However when I type tsc expecting my sample file to convert from ts to js I got another ts file.
What did I do wrong
You can watch I what i did by clicking here (this was a personal video tutorial I was creating!)
My question is simple:
1.What did I do wrong?
2.How do I fix it?
This is my tsconfig.json code
{
"compilerOptions": {
/* Basic Options */
"target": "es6", /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */
"module": "commonjs", /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
"moduleResolution": "node",
"inlineSourceMap": true,
"declaration": false,
"noImplicitAny": false,
"sourceMap": false,
"removeComments": false,
// "lib": [], /* Specify library files to be included in the compilation. */
// "allowJs": true, /* Allow javascript files to be compiled. */
// "checkJs": true, /* Report errors in .js files. */
// "jsx": "preserve", /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
// "declaration": true, /* Generates corresponding '.d.ts' file. */
// "declarationMap": true, /* Generates a sourcemap for each corresponding '.d.ts' file. */
// "sourceMap": true, /* Generates corresponding '.map' file. */
// "outFile": "./", /* Concatenate and emit output to single file. */
"outDir": "JSFiles", /* Redirect output structure to the directory. */
// "rootDir": "./", /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
// "composite": true, /* Enable project compilation */
// "removeComments": true, /* Do not emit comments to output. */
// "noEmit": true, /* Do not emit outputs. */
// "importHelpers": true, /* Import emit helpers from 'tslib'. */
// "downlevelIteration": true, /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
// "isolatedModules": true, /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
/* Strict Type-Checking Options */
/* Enable all strict type-checking options. */
// "noImplicitAny": true, /* Raise error on expressions and declarations with an implied 'any' type. */
// "strictNullChecks": true, /* Enable strict null checks. */
// "strictFunctionTypes": true, /* Enable strict checking of function types. */
// "strictBindCallApply": true, /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
// "strictPropertyInitialization": true, /* Enable strict checking of property initialization in classes. */
// "noImplicitThis": true, /* Raise error on 'this' expressions with an implied 'any' type. */
// "alwaysStrict": true, /* Parse in strict mode and emit "use strict" for each source file. */
/* Additional Checks */
// "noUnusedLocals": true, /* Report errors on unused locals. */
// "noUnusedParameters": true, /* Report errors on unused parameters. */
// "noImplicitReturns": true, /* Report error when not all code paths in function return a value. */
// "noFallthroughCasesInSwitch": true, /* Report errors for fallthrough cases in switch statement. */
/* Module Resolution Options */
// "moduleResolution": "node", /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
// "baseUrl": "./", /* Base directory to resolve non-absolute module names. */
// "paths": {}, /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
// "rootDirs": [], /* List of root folders whose combined content represents the structure of the project at runtime. */
// "typeRoots": [], /* List of folders to include type definitions from. */
// "types": [], /* Type declaration files to be included in compilation. */
// "allowSyntheticDefaultImports": true, /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
"esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
// "preserveSymlinks": true, /* Do not resolve the real path of symlinks. */
/* Source Map Options */
// "sourceRoot": "", /* Specify the location where debugger should locate TypeScript files instead of source locations. */
// "mapRoot": "", /* Specify the location where debugger should locate map files instead of generated locations. */
// "inlineSourceMap": true, /* Emit a single file with source maps instead of having a separate file. */
// "inlineSources": true, /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
/* Experimental Options */
// "experimentalDecorators": true, /* Enables experimental support for ES7 decorators. */
// "emitDecoratorMetadata": true, /* Enables experimental support for emitting type metadata for decorators. */
},
"exclude": [
"node_modules"
]
}

Can you try this tsconfig file -
{
"compilerOptions": {
"module": "commonjs",
"target": "es6",
"moduleResolution": "node",
"sourceMap": false,
"declaration": false,
"removeComments": false,
"noImplicitAny": false,
"skipLibCheck": true,
"outDir": "JSFiles",
"typeRoots": [ "./node_modules/#types" ],
"types": ["node"]
},
"exclude": [
"node_modules",
"typescript"
]
}

How do I target ES2018 in TypeScript?

I am targeting ES2018 and do not care about ES3 or ES5. From my tsconfig.json: "target": "ES2018". tsc complains:
An async function or method in ES5/ES3 requires the 'Promise' constructor. Make
sure you have a declaration for the 'Promise' constructor or include 'ES2015' in your --lib option.
I know I could add "lib": ["es2015"] to add libraries to the compilation but I don't need those libraries, I am targeting ES2018.
How do I target ES2018 in TypeScript?
Here is my tsconfig.json:
{
"compilerOptions": {
/* Basic Options */
"target": "ES2018" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */,
"module": "commonjs" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */,
"lib": ["es2015"] /* Specify library files to be included in the compilation. */,
// "allowJs": true, /* Allow javascript files to be compiled. */
// "checkJs": true, /* Report errors in .js files. */
// "jsx": "preserve", /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
// "declaration": true, /* Generates corresponding '.d.ts' file. */
// "declarationMap": true, /* Generates a sourcemap for each corresponding '.d.ts' file. */
// "sourceMap": true, /* Generates corresponding '.map' file. */
// "outFile": "./", /* Concatenate and emit output to single file. */
// "outDir": "./", /* Redirect output structure to the directory. */
// "rootDir": "./", /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
// "composite": true, /* Enable project compilation */
// "removeComments": true, /* Do not emit comments to output. */
// "noEmit": true, /* Do not emit outputs. */
// "importHelpers": true, /* Import emit helpers from 'tslib'. */
// "downlevelIteration": true, /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
// "isolatedModules": true, /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
/* Strict Type-Checking Options */
"strict": true /* Enable all strict type-checking options. */,
// "noImplicitAny": true, /* Raise error on expressions and declarations with an implied 'any' type. */
// "strictNullChecks": true, /* Enable strict null checks. */
// "strictFunctionTypes": true, /* Enable strict checking of function types. */
// "strictPropertyInitialization": true, /* Enable strict checking of property initialization in classes. */
// "noImplicitThis": true, /* Raise error on 'this' expressions with an implied 'any' type. */
// "alwaysStrict": true, /* Parse in strict mode and emit "use strict" for each source file. */
/* Additional Checks */
// "noUnusedLocals": true, /* Report errors on unused locals. */
// "noUnusedParameters": true, /* Report errors on unused parameters. */
// "noImplicitReturns": true, /* Report error when not all code paths in function return a value. */
// "noFallthroughCasesInSwitch": true, /* Report errors for fallthrough cases in switch statement. */
/* Module Resolution Options */
// "moduleResolution": "node", /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
// "baseUrl": "./", /* Base directory to resolve non-absolute module names. */
// "paths": {}, /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
// "rootDirs": [], /* List of root folders whose combined content represents the structure of the project at runtime. */
// "typeRoots": [], /* List of folders to include type definitions from. */
// "types": [], /* Type declaration files to be included in compilation. */
// "allowSyntheticDefaultImports": true, /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
"esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
// "preserveSymlinks": true, /* Do not resolve the real path of symlinks. */
/* Source Map Options */
// "sourceRoot": "", /* Specify the location where debugger should locate TypeScript files instead of source locations. */
// "mapRoot": "", /* Specify the location where debugger should locate map files instead of generated locations. */
// "inlineSourceMap": true, /* Emit a single file with source maps instead of having a separate file. */
// "inlineSources": true, /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
/* Experimental Options */
// "experimentalDecorators": true, /* Enables experimental support for ES7 decorators. */
// "emitDecoratorMetadata": true, /* Enables experimental support for emitting type metadata for decorators. */
}
}

Just add ES2018 to lib in tsconfig.json:
"lib": [
"ES2018"
]
lib is different to target. target roughly means the JavaScript version of the generated output files. lib means the features you will use in TypeScript. For example, you can use new features in ES2018 ("lib": ["ES2018"]), but still target at ES6 ("target": "ES6"). Those new features will be translated to ES6 during compilation (this may be done via third party tools like babel, and some new features may not be translatable, but these are just implementation details).