I need to implement a string concatenate function, the functionality shows below,
function concatenation(original: string, name1?, name2?){
return original + name1 + name2;
}
However, the question is, there can be more parameters about name; therefore, this is a not a good coding style. I want to change its like shows below.
function concatenation(original: string, name?:[string]){
return original + ...name1;
}
But in this way, the program will report an error. How could I achieve it?
You can use rest with join as:
function concatenation(original: string, name1?, name2?) {
return original + name1 + name2;
}
concatenation('Original', 'Name1', 'Name2', 'Name3');
This can handle any number of string arguments
function concatenation2(...names: string[]) {
return names.join('');
}
concatenation2('Original', 'Name1', 'Name2', 'Name3');
function concatenation2(...names) {
return names.join('');
}
console.log(concatenation2('Original', 'Name1', 'Name2', 'Name3'));Providing your error report will make it easier to discover your real problem.
In fact, what your function concatenation actually do is simply concating multiple string variables, though you tried to distinguish them by name. Since you want to place the variables in the arguments of the function, you could simply using destructuring assignment.
function concatenation(...items) {
// `items` is an Array consisting of all the function arguments.
items.join('');
}
concatenation(1,2,3) // "123"
concatenation("a", "bcd", "ef", "g", "h") // "abcdefgh"
And, please note that you can't use TypeScript type annotations in JavaScript. Also the type annotations in the question description is actually not legal.
You cannot destructure javascript object with any type of arithmetic operator like ( +, - , etc...).
function concatenation(original: string, names?: [string]) {
return `${original}${names.split("")}`;
}
concatenation("original", ["name1", "name2", "name3"]);