Bypassing disputes in a TypeScript function

I attempted to implement the solution provided by Pacerier in response to the question about skipping arguments in a JavaScript function. However, it doesn't seem to be working for me.

The function I am dealing with has numerous arguments.

this.service.list("all",null, null, localStorage.getItem('currentProgram'), null, 100, ...Array(2), environment.liveMode).subscribe(...)

My only workaround so far has been to manually write out each argument one by one, such as (,null, null or undefined,undefined).

I even created a test method to experiment with, but unfortunately, that didn't yield any successful results either.

test(a: any, b: any, c: any, d: string) {
    console.log(d)
}

ngOnInit() {
    this.test(...Array(3), "a")
}

I also tested other syntax options mentioned in the answer.

Is there a more concise way to achieve this in TypeScript?

angulartypescriptfunctionargumentsspread

Answer №1

In TypeScript, when you need to skip a parameter, you must explicitly pass either undefined or null as the parameter value. Here's an example:

function myFunction(param1?: string, param2?: number, param3?: boolean) {
// do something
}

myFunction(,,true); // ❌ Error
myFunction(...[,,], true); // ❌ Error
myFunction(...Array(2), true); // ❌ Error
myFunction(undefined, undefined, true); // ✅ Works 
myFunction(null, null, true); // ✅ Works

To learn more about this topic and see additional examples, refer to the TypeScript documentation section on optional parameters: https://www.typescriptlang.org/docs/handbook/2/functions.html#optional-parameters

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