typescript - what different between import * as module and import module in javascript - Stack Overflow

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When I write typescript:

I have this code:

import * as express from 'express'

and the system gives me an error:

Type originates at this import. A namespace-style import cannot be called or constructed, and will cause a failure at runtime. Consider using a default import or import require here instead.

So, I change to:

import express from 'express'

what is the difference between them, why the first way can not called or constructed?

When I write typescript:

I have this code:

import * as express from 'express'

and the system gives me an error:

Type originates at this import. A namespace-style import cannot be called or constructed, and will cause a failure at runtime. Consider using a default import or import require here instead.

So, I change to:

import express from 'express'

what is the difference between them, why the first way can not called or constructed?

• javascript
• typescript
• import

Share Improve this question Follow asked Apr 30, 2019 at 5:12 user504909user504909 9,5591616 gold badges7474 silver badges113113 bronze badges 1

• as is used when you want to give alias name. – random Commented Apr 30, 2019 at 5:14

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1 Answer 1

Sorted by: Reset to default 8

what is the difference between them

• * as express will import the entire contents of a module
• express is will import the default export only

why the first way can not called or constructed?

A module itself is not callable as per the ES spec. So you wouldn't be able to do express() i.e. a function invocation. Therefore it must mapped to a member of the module, in this case the default export member

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