Typescript Interface SyntaxError: Unexpected identifier at interface name

Question

I'm new to Typescript and I'm still figuring my way out, I searched this problem everywhere otherwise I wont be asking this question. I have a SyntaxError at the interface name and don't know how to solve it. Here is my short code:

interface Cars {
    name:string
    model:string
    topSpeed:number
    colors:string[]
    speedPrint(carSpeed:number):void
}

class BMW implements Cars{
    name = 'BMW X6'
    model = 'S'
    topSpeed = 320
    colors = ['cobalt red','phantom blue','white']
    speedPrint(topSpeed:number):void{
        console.log(`My car top speed is ${topSpeed}`)
    }
}

and this is the error:

app.ts:1
interface Cars {
          ^^^^

SyntaxError: Unexpected identifier
    at wrapSafe (internal/modules/cjs/loader.js:979:16)
    at Module._compile (internal/modules/cjs/loader.js:1027:27)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
    at Module.load (internal/modules/cjs/loader.js:928:32)
    at Function.Module._load (internal/modules/cjs/loader.js:769:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)
    at internal/main/run_main_module.js:17:47

You need to provide far more info. See my partial answer.

Inigo
– Inigo

2021-07-04 04:04:25 +00:00
Commented Jul 4, 2021 at 4:04 — Inigo
– Inigo, Commented Jul 4, 2021 at 4:04

Inigo · Accepted Answer · 2025-01-03 14:48:51Z

10

There is no Typescript syntax error in your code. You can see that it has no errors at all in the Typescript playground.

But from the stacktrace it appears that you are trying to execute the Typescript directly from Node.js as if it were Javascript. That would explain the error because Javascript does not support interfaces; it's a Typescript thing.

You can compile or transpile the *.ts files to *.js using a tool like tsc, esbuild, deno or bun.

Or you can run Typescript directly using tsx or ts-node. Node.js has recently (Node v22.6.0, 2024) added experimental support for running Typescript directly like this:

node --experimental-strip-types example.ts

I can't give you a more specific answer without you providing more info about your setup, the command you executed that produced that error, etc.

edited Jan 3 at 14:48

answered Jul 4, 2021 at 4:03

Inigo

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3 Comments

youssef abdulaziz Over a year ago

Thanks for explanation, I was trying to get the logs in the VS Code like the tutorial I`m following but I think I missed something there.

youssef abdulaziz Over a year ago

That was the first thing i thought of after reading your answer, but I couldn't because I don't have a 15 reputation yet.

Ben P Over a year ago

you have to compile your typescript file first and then run the compiled js file. I am getting similar error and resolved by doing below: tsc hash-map.ts && node hash-map.js

XouDo · Accepted Answer · 2021-09-02 08:07:16Z

7

I was facing the same error but I did the following and it works:

Install ts by typing this command in the terminal npm install -g typescript
After this type tsc filename.ts
Then node ./file.js (not ts) and see what gonna happen on the terminal

edited Sep 2, 2021 at 8:07

XouDo

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answered Sep 1, 2021 at 19:37

Gregg m

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Comments

Sarath Baiju · Accepted Answer · 2022-01-18 10:31:42Z

2

I think instead of run node .ts you can run

tsc .ts
node .js Because when you run the first command, it will generate the equivalent javascript file corresponds to your typescript file.

answered Jan 18, 2022 at 10:31

Sarath Baiju

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