Typescript assert non null

interface Foo { bar(): void }
declare function getFoo(): Foo | undefined;

function assert(value: unknown): asserts value {
    if (value === undefined) {
        throw new Error('value must be defined');
    }
}

function test() {
    const foo = getFoo();
    // foo is Foo | undefined here
    assert(foo);
    // foo narrowed to Foo
    foo.bar();
}

Source: stackoverflow.com

Similar codes

1 vote105 views1 answer
Check if string include numbers in typescript
TypeScript
14 votes113 views6 answers
How to install bootstrap in angular 11
TypeScript
2 votes140 views1 answer
Laravel model dont exists id
TypeScript
3 votes169 views1 answer
Typescript == vs ===
TypeScript
-1 vote112 views1 answer
What are the components of the environment? Explain it along with the examples.
TypeScript
0 vote113 views1 answer
Spilit with comma in ts
TypeScript
0 vote102 views1 answer
How to take list as command line arguments in python
TypeScript
32 votes98 views1 answer
Ng : File C:\Users\nEW u\AppData\Roaming\npm\ng.ps1 cannot be loaded. The file C:\Users\nEW u\AppData\Roaming\npm\ng.ps1 is setting execution policy, see about_Execution_Policies at https:/go.microsoft.com/fwlink/?LinkID=135170. At line:1 char:1
TypeScript
0 vote93 views1 answer
How to pass data between requests
TypeScript
3 votes101 views1 answer
Hosts
TypeScript