Handling spread of a union of tuples in TypeScript

Handling spread of a union of tuples in TypeScript

If you have been working with TypeScript, you might have come across a situation where you need to handle the spread of a union of tuples. This can be a bit tricky, but fear not, we have some solutions for you.

Solution 1: Using a type guard

One way to handle the spread of a union of tuples is by using a type guard. This involves checking the type of the tuple and then using the spread operator accordingly. Here’s an example:

type Tuple = [string, number] | [boolean, string];

function handleSpread(tuple: Tuple) {
  if (Array.isArray(tuple)) {
    const [a, b] = tuple;
    // Do something with a and b
  } else {
    const [a, b, c] = tuple;
    // Do something with a, b, and c
  }
}

// Usage
handleSpread(["hello", 42]); // Tuple is [string, number]
handleSpread([true, "world", 42]); // Tuple is [boolean, string]

In this example, we have a type guard that checks if the tuple is an array. If it is, we destructure the array into variables a and b. If it’s not, we destructure it into variables a, b, and c. You can then perform the desired operations based on the number of elements in the tuple.

Solution 2: Using a discriminated union

Another solution is to use a discriminated union. This involves adding a discriminant property to each tuple in the union, which can be used to determine the type of the tuple. Here’s an example:

type Tuple = [string, number] | [boolean, string];

function handleSpread(tuple: Tuple) {
  if ("0" in tuple) {
    const [a, b] = tuple;
    // Do something with a and b
  } else {
    const [a, b, c] = tuple;
    // Do something with a, b, and c
  }
}

// Usage
handleSpread(["hello", 42]); // Tuple is [string, number]
handleSpread([true, "world", 42]); // Tuple is [boolean, string]

In this example, we check if the property “0” exists in the tuple. If it does, we destructure the tuple into variables a and b. If it doesn’t, we destructure it into variables a, b, and c. This way, we can determine the type of the tuple based on the presence of the discriminant property.

These are two solutions for handling the spread of a union of tuples in TypeScript. Choose the one that suits your needs and implement it in your code. Happy coding!

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Handling spread of a union of tuples in TypeScript If you have been working with TypeScript, you might have come across a situation where you need to handle the spread of a union of tuples. This can be a bit tricky, but fear not, we have some solutions for you. Solution 1: Using a type guard One way to handle the spread of a union of tuples is by using a type guard. This involves checking the type of the tuple and then using the spread operator accordingly. Here's an example: type Tuple = [string, number] | [boolean, string]; function handleSpread(tuple: Tuple) { if (Array.isArray(tuple)) { const [a, b] = tuple; // Do something with a and b } else { const [a, b, c] = tuple; // Do something with a, b, and c } } // Usage handleSpread(["hello", 42]); // Tuple is [string, number] handleSpread([true, "world", 42]); // Tuple is [boolean, string] In this example, we have a type guard that checks if the tuple is an array. If it is, we destructure the array into variables a and b. If it's not, we destructure it into variables a, b, and c. You can then perform the desired operations based on the number of elements in the tuple. Solution 2: Using a discriminated union Another solution is to use a discriminated union. This involves adding a discriminant property to each tuple in the union, which can be used to determine the type of the tuple. Here's an example: type Tuple = [string, number] | [boolean, string]; function handleSpread(tuple: Tuple) { if ("0" in tuple) { const [a, b] = tuple; // Do something with a and b } else { const [a, b, c] = tuple; // Do something with a, b, and c } } // Usage handleSpread(["hello", 42]); // Tuple is [string, number] handleSpread([true, "world", 42]); // Tuple is [boolean, string] &lt Share this:FacebookX Related Posts: How Extract type from union by its field type How to Extract a Type from a Union by its Field Type in TypeScript When working with TypeScript, you may... Explanation of Tuple Explanation of Tuple When working with TypeScript, you may come across the term “Tuple” and wonder what it means. In... How do I Exclude or Select Tuples by membership? How do I Exclude or Select Tuples by membership? When working with TypeScript, you may come across situations where you... How to test Functional Router Guard with Parameter within runInInjectionContext How to test Functional Router Guard with Parameter within runInInjectionContext When working with TypeScript, testing functional router guards with parameters...