Import vs Require in Typescript

Question

While I was going through Angular2 documentation, I came across below code in here.

src/polyfills.ts

import 'core-js/es6';
import 'core-js/es7/reflect';
require('zone.js/dist/zone');

if (process.env.ENV === 'production') {
 // Production
} else {
 // Development
Error['stackTraceLimit'] = Infinity;
require('zone.js/dist/long-stack-trace-zone');
}

In the above code we can see that there are both import and require statements.

"core-js" and "zone.js" are both node modules.

My question is; why is import used for core-js and require for "zone.js", is there any specific reason for this?

score 37 · Accepted Answer · answered Sep 23 '16 at 10:20

37

With TypeScript, import can be used if there is a declaration file (see Declaration Files in basarat's book) for the module.

If there isn't a declaration file, the TypeScript compiler doesn't know if the module exists, so you need to use require instead which lacks the compilation checking.

answered Sep 23 '16 at 10:20

James Monger

10,181
7
62
98

I am not sure if that is correct , because I observed that for "core-js/es7/reflect" , only .js file exists , there is no .ts or .d.ts file – refactor Sep 23 '16 at 10:34
On the link you provided, right at the top, look in the "typings.json" section. The typings for core-js have been included, which will give the .d.ts files :) – James Monger Sep 23 '16 at 10:40
4

zone.js does now include a .d.ts file and can be imported using `import` – danwellman Jun 14 '17 at 08:27
1

Is there a way to make visual studio go for import->from over require? alt+enter always performs require – John Demetriou Jun 11 '20 at 06:48
The link is broken. https://basarat.gitbook.io/typescript/type-system/intro/d.ts ? – Thomas Weller Dec 16 '22 at 20:36

Import vs Require in Typescript

1 Answers1

Linked