Category: TypeScript

Sometimes, we want to use the array reduce function with TypeScript.

In this article, we’ll look at how to use the array reduce function with TypeScript.

How to use the array reduce function with TypeScript?

To use the array reduce function with TypeScript, we can use it like we do with JavaScript.

For instance, we write

const x = a.reduce(fn, <string[]>[]);

to call reduce with the fn callback and an empty array as the initializer.

We set the initializer array to a string array with <string[]>.

Conclusion

To use the array reduce function with TypeScript, we can use it like we do with JavaScript.

Sometimes, we want to compile to a single file with TypeScript.

In this article, we’ll look at how to compile to a single file with TypeScript.

How to compile to a single file with TypeScript?

To compile to a single file with TypeScript, we remove the module option and add the outFile option in tsconfig.json.

For instance, we write

{
  "compilerOptions": {
    "target": "ES5",
    "removeComments": true,
    "preserveConstEnums": true,
    "outFile": "./build/build.js",
    "sourceRoot": "./src/",
    "rootDir": "./src/",
    "sourceMap": true
  }
}

in tsconfig.json.

We set outFile to ./build/build.js so that the TypeScript compiler will compile all the code into that file.

We remove the module option so that the code will be compiled into one file.

Conclusion

To compile to a single file with TypeScript, we remove the module option and add the outFile option in tsconfig.json.

Sometimes, we want to convert a variable to boolean with TypeScript.

In this article, we’ll look at how to convert a variable to boolean with TypeScript.

How to convert a variable to boolean with TypeScript?

To convert a variable to boolean with TypeScript, we can use the Boolean function.

For instance, we write

const x = Boolean(someVal);

to call Boolean with someVal to return the truth value of the someVal variable.

Then we assign the returned value to x.

Conclusion

To convert a variable to boolean with TypeScript, we can use the Boolean function.

Sometimes, we want to use RegExp in TypeScript.

In this article, we’ll look at how to use RegExp in TypeScript.

How to use RegExp in TypeScript?

To use RegExp in TypeScript, we can use it as we do with JavaScript.

For instance, we write

const trigger = "2";
const regexp = new RegExp("^[1-9]d{0,2}$");
const test = regexp.test(trigger);

to create a new regex with the RegExp constructor that matches any number with 0 to 2 digits.

Then we call test with the trigger string to see if it matches.

Conclusion

To use RegExp in TypeScript, we can use it as we do with JavaScript.

Sometimes, we want to fix the "Argument of type ‘X’ is not assignable to parameter of type ‘X’" error with TypeScript.

In this article, we’ll look at how to fix the "Argument of type ‘X’ is not assignable to parameter of type ‘X’" error with TypeScript.

How to fix the "Argument of type ‘X’ is not assignable to parameter of type ‘X’" error with TypeScript?

To fix the "Argument of type ‘X’ is not assignable to parameter of type ‘X’" error with TypeScript, we should restart VS Code to clear the error.

We should also make sure our code has no syntax errors.

Once we restart VS Code and the syntax errors are removed, the error should clear.

Conclusion

To fix the "Argument of type ‘X’ is not assignable to parameter of type ‘X’" error with TypeScript, we should restart VS Code to clear the error.

We should also make sure our code has no syntax errors.