how to resolve the error ts.(2345) in angular?-CodePudding

error -Argument of type 'string | null' is not assignable to parameter of type 'string'. Type 'null' is not assignable to type 'string'.ts(2345) there are 2 error in this code 1st in line no.27 and 2nd in line no.32.

CodePudding user response：

Always share some code with it, its impossible to decode it for you. But the error happens in the following case:

let myVar = null;

// ..

myVar = 'assigned a string';

Solution: define the type for myVar to be:

let myVar: string|null

CodePudding user response：

your typescript error is telling you that you are trying to assign a variable of type string | null to a variable that expects a string instead. ex:

let x : string | null = 'something'

function doSomething(foo: string) {
 ...
}

doSomething(x)

this is a simple example. For example, you can use the typescript guards:

let x : string | null = 'something'

function doSomething(foo: string) {
 ...
}

if(typeof x === 'string') {
 doSomething(x)
}

here you can read about.

or you can type casting like:

let x : string | null = 'something'

function doSomething(foo: string) {
 ...
}


doSomething(<string>x)

Typescript is strinct but will help you to avoid boring erros

Good Coding!