TYPESCRIPT

how to make a parameter optional in typescript

// Optional parameter
function foo(x?: number) {
    console.log("x : "+ x);
}
foo();
foo(6);

how to define optional parameter in typescript

function functionName(par1: number, par2?: number) {

}

typescript make function argument optional

        
            
        
     function multiply(a: number, b: number, c?: number): number {

    if (typeof c !== 'undefined') {
        return a * b * c;
    }
    return a * b;
}

add optional parameters javascript or typescript function

function newsArticle(options: newsArticleOptions) {
    const {
        showHeadline = true,
        showDate = true,
        articleType = "World"
    } = options;
}

// Use like this
newsArticle({ articleType: "Tech" });

// Of course, don't write JavaScript without TypeScript
interface newsArticleOptions {
    showHeadline?: boolean
    showDate?: boolean
    articleType?: articleType
}

type articleType = "Tech" | "World" | "Sports"