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attempt

TS JS Deno

Attempts to invoke a function with the provided arguments, returning either the result or the caught error object.

Use a try... catch block to return either the result of the function or an appropriate error.

typescript
const attempt = (fn: (...args: any[]) => any, ...args: any[]) => {
try {
return fn(...args);
} catch (e) {
return e instanceof Error ? e : new Error(e);
}
};
typescript
let elements = attempt(function (selector) {
return document.querySelectorAll(selector);
}, ">_>");
if (elements instanceof Error) elements = []; // elements = []

const isValidNumber = (num: number) => {
if (num >= 0) {
return num;
}
throw new Error("Invalid number");
};
const ten = attempt(isValidNumber, 10);
assertEquals(ten, 10);

const error = attempt(isValidNumber, -1);
assertEquals(error instanceof Error, true);
assertEquals(error.message, "Invalid number");

attempt2

Same as attempt but it return tuple of result and error.

typescript
const attempt2 = (fn: (...args: any[]) => any, ...args: any[]) => {
try {
return [fn(...args), null];
} catch (e) {
return [null, e instanceof Error ? e : new Error(e)];
}
};
typescript
let [elements, error] = attempt2(function (selector) {
return document.querySelectorAll(selector);
}, ">_>");
if (error instanceof Error) elements = []; // elements = []

const isValidNumber = (num: number) => {
if (num >= 0) {
return num;
}
throw new Error("Invalid number");
};
const [ten] = attempt2(isValidNumber, 10);
assertEquals(ten, 10);

const [res, error] = attempt2(isValidNumber, -1);
assertEquals(res, null);
assertEquals(error instanceof Error, true);
assertEquals(error.message, "Invalid number");