CODEWITHSUNDEEP
typescript
POV
POV

Reputation: 12015

How to use function in map TypeScript?

I have defined a function that I want to pass to .map:

export let disableTabsByRights = (permissions: string[], type: string) => permissions.includes(type);

export let disableTabsByUsers = ();

Where this.tabs is array:

do(fn: Function) {
    this.tabs = this.tabs.map((item) => {
     item.disabled = fn(item.type); 
     return item;
    });
}

I want to call outside

do(disableTabsByRights(["VIEW"]));

Why it does not work for me?

So I want to change easy realizations?

Upvotes: 0

Views: 1519

Answers (1)

spender
spender

Reputation: 120498

Your do function requires that a function is passed to it, but by passing disableTabsByRights(["VIEW"]), you're passing the return value of the invocation disableTabsByRights(["VIEW"], undefined) instead of a function.

Let's pass it an actual function instead, that takes a type string and returns a boolean value:

do(type => disableTabsByRights(["VIEW"], type))

would do the trick.

Otherwise, you could redefine the function as a higher-order function

export let disableTabsByRights = 
    (permissions: string[]) => 
    (type: string) => 
        permissions.includes(type);

So, now, we can call disableTabsByRights with a single parameter (permissions), and it will return another function with a single parameter (type) which already has a resolved permissions value.

To fully call this H-O function, you'd need to disableTabsByRights(["somePerm"])("someType")

Now you can use it as you first attempted:

do(disableTabsByRights(["VIEW"])); //now disableTabsByRights(["VIEW"]) returns a function.

As an aside, you could improve your code by specifying the exact shape of the function being passed in:

do(fn: (type:string) => boolean) { /*...*/ }

to enforce better type-safety.

Upvotes: 1

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