How to compile multiple Typescript files into a single file ?

In this article, we will learn how to compile multiple Typescript files into a single file. There are two approaches that can be followed here:

Approach 1: Compiling multiple Typescript files into a single JavaScript file. We simply use the following syntax:

Syntax:

tsc --out outputFile.js typeScriptFile1.ts typeScriptFile2.ts ... typeScriptFilen.ts

Explanation: 

• tsc: It stands for TypeScript compiler which is used to invoke the compiler in order to compile the TypeScript files.
• --out: It is a CLI (Command Line Interface) command which concatenates the TypeScript files and emits the output to a single JS file.
• outputFile.js: The JavaScript file which holds the result of the compilation of the TypeScript files.
• typeScriptFile1, typeScriptFile2 ... typeScriptFilen: The TypeScript files to be compiled.

Example: Here, three TypeScript files with the names script.ts, index.ts and app.ts are compiled to a single JavaScript file output.js. Subsequently, the JavaScript file is executed by using the following CLI command: 

node output.js

const myArr = [1, 2, 3, 4, 5];

console.log("CONTENTS OF FILE 1");

for (let i = 0; i < myArr.length; i++) {
  console.log(myArr[i]);
}

const GFG = ["Geeks", "For", "Geeks"];

console.log("\nCONTENTS OF FILE 2");

for (let i = 0; i < GFG.length; i++) {
  console.log(GFG[i]);
}

const geeks = [true, false, 2.5, 5];

console.log("\nCONTENTS OF FILE 3");

for (let i = 0; i < geeks.length; i++) {
  console.log(geeks[i]);
}

Generated output JavaScript file "output.js"

var myArr = [1, 2, 3, 4, 5];

console.log("CONTENTS OF FILE 1");

for (var i = 0; i < myArr.length; i++) {
    console.log(myArr[i]);
}

var GFG = ["Geeks", "For", "Geeks"];

console.log("\nCONTENTS OF FILE 2");

for (var i = 0; i < GFG.length; i++) {
    console.log(GFG[i]);
}

var geeks = [true, false, 2.5, 5];

console.log("\nCONTENTS OF FILE 3");

for (var i = 0; i < geeks.length; i++) {
    console.log(geeks[i]);
}

Output:

Approach 2: Compiling multiple Typescript files into a single TypeScript file. We use the following syntax:

Syntax:

tsc --out outputFile.ts typeScriptFile1.ts typeScriptFile2.ts ... typeScriptFilen.ts

Explanation:

• tsc: It stands for TypeScript compiler which is used to invoke the compiler in order to compile the TypeScript files.
• --out: It is a CLI (Command Line Interface) command which concatenates the TypeScript files and emits the output to a single TypeScript file
• outputFile.ts: The TypeScript file which holds the result of the compilation of the TypeScript files
• typeScriptFile1, typeScriptFile2 ... typeScriptFilen: The TypeScript files to be compiled.

Example: Here, three TypeScript files with the names file1.ts, file2.ts and file3.ts are compiled to a single TypeScript file output.ts. After that, the resultant TypeScript file is compiled to a JavaScript file output.js and then the JavaScript file is executed by using the following CLI commands: 

tsc output.ts
node output.js

let i = 1;
console.log("CONTENTS OF FILE 1");
while (i <= 5) {
  console.log(i);
  i++;
}

console.log("\nCONTENTS OF FILE 2");
console.log("GeeksForGeeks is a computer science portal for geeks.");

const geeks = [2, 4, 6, 8];
console.log("\nCONTENTS OF FILE 3");
for (let i = 0; i < geeks.length; i++) {
  console.log(geeks[i]);
}

Generated output TypeScript file "output.ts"

var i = 1;
console.log("CONTENTS OF FILE 1");
while (i <= 5) {
    console.log(i);
    i++;
}
console.log("\nCONTENTS OF FILE 2");
console.log("GeeksForGeeks is a computer science portal for geeks.");
var geeks = [2, 4, 6, 8];
console.log("\nCONTENTS OF FILE 3");
for (var i_1 = 0; i_1 < geeks.length; i_1++) {
    console.log(geeks[i_1]);
}

Generated output JavaScript file "output.js"

var i = 1;
console.log("CONTENTS OF FILE 1");
while (i <= 5) {
    console.log(i);
    i++;
}
console.log("\nCONTENTS OF FILE 2");
console.log("GeeksForGeeks is a computer science portal for geeks.");
var geeks = [2, 4, 6, 8];
console.log("\nCONTENTS OF FILE 3");
for (var i_1 = 0; i_1 < geeks.length; i_1++) {
    console.log(geeks[i_1]);
}

Output: