TypeScript complaining when trying to use a function as .replace argument

Question

I have an array of objects for a replace function, which is inside a forEach loop (I did this so I wouldn't have to write .replace again and again). The replacement can either be a string or a function:

const content = `'Example'
"Another example

"Another example"`

const regexes = [{
  }, {
    name: 'apostrophe',
    pattern: /(?<=\w)\'(?=\w)|(?<=\w)\'(?!\w)/g,
    replacement: '&rsquo;'
  }, {
    name: 'doubleQuotes',
    pattern: /"([^"\n\r]*)("|$)/gm,
    replacement: (x: any,y: any,z: any) =>  z === '"' ? `&ldquo;${y}&rdquo;` : `&ldquo;${y}`
}]

regexes.forEach(regex => {
  content = content.replace(regex.pattern, regex.replacement)
})

TypeScript (inside VS Code) is throwing this type error:

Argument of type 'string | ((x: any, y: any, z: any) => string)' is not assignable to parameter of type '(substring: string, ...args: any[]) => string'.

Type 'string' is not assignable to type '(substring: string, ...args: any[]) => string'.ts(2769)

I think TypeScript is complaining that one of the replacement is a function?

What should I change in the code to remove this type error?

Here's there live code (I fixed the issues raised by the answer below.)

Share all the relevant code at typescriptlang.org/play/?#code/Q — k.tten
– k.tten, Commented Mar 24, 2022 at 15:41

mizerlou · Accepted Answer · 2022-03-24 17:31:08Z

1

first, remove the empty entry from regexes or handle the empty entry in the forEach. you also need to define content with a let instead of const, since you're modifying the value.

for the apostrophe replacement, try using () => '’' instead of just a string. that will align the types of your replacement field, making them all functions and the compiler will be happy.

answered Mar 24, 2022 at 17:31

mizerlou

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1 Comment

wyc Over a year ago

Thanks for the answer. I'm curious, is there a way of making this work without making the first replacement a function?

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