define is not defined in nodejs typescript app
<p>I am working on nodejs app in typescript in which i have wrote  a file server.js  as fallow  :</p>

<pre><code>import express = require('express');
import mongoose = require('mongoose');


let app=express();
app.set('port', process.env.PORT || 3000); // Set port to 3000 or the provided PORT variable


/**
 * Start app 
 */
app.listen(app.get('port'), function() {
  console.log(`App listening on port ${app.get('port')}!`);
});
</code></pre>

<p>i have use the gulp to traspile it which  generate js file as</p>

<pre><code>define(["require", "exports", 'express'], function (require, exports, express) {
    var app = express();
    app.set('port', process.env.PORT || 3000); // Set port to 3000 or the provided PORT variable
    /**
     * Start app
     */
    app.listen(app.get('port'), function () {
        console.log("App listening on port " + app.get('port') + "!");
    });
});

//# sourceMappingURL=../map/server.js.map
</code></pre>

<p>but when i run this file am getting error define is not define. </p>

<p>Please correct me if i am doing any mistake.</p>

<p><a href="https://i.stack.imgur.com/krChZ.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/krChZ.jpg" alt="enter image description here"></a></p>