how to compile typescript to javascript code example

Example 1: how to run typescript file

npx ts-node src/foo.ts

Example 2: typescript compile string to js

// compile.ts

import * as ts from "typescript";

function tsCompile(source: string, options: ts.TranspileOptions = null): string {
    // Default options -- you could also perform a merge, or use the project tsconfig.json
    if (null === options) {
        options = { compilerOptions: { module: ts.ModuleKind.CommonJS }};
    }
    return ts.transpileModule(source, options).outputText;
}

// Make sure it works
const source = "let foo: string  = 'bar'";

let result = tsCompile(source);

console.log(result); // var foo = 'bar';

Example 3: how to compile ts in cmd

"scripts": {
    "clean": "rimraf dist",
    "start": "npm-run-all clean --parallel watch:build watch:server --print-label",
    "watch:build": "tsc --watch",
    "watch:server": "nodemon './dist/index.js' --watch './dist'"
}