Author: John Au-Yeung

Sometimes, we want to compare enums in TypeScript.

In this article, we’ll look at how to compare enums in TypeScript.

How to compare enums in TypeScript?

To compare enums in TypeScript, we can assign a value to each enum so we can compare them easily.

For instance, we write

enum AnimalInfo {
  Tiger = "Tiger",
  Lion = "Lion",
}

let tigerStr = "Tiger";

if (tigerStr === AnimalInfo.Tiger) {
  console.log("true");
} else {
  console.log("false");
}

to create the AnimalInfo enum which has values assigned to each entry.

Then we compare tigerStr to AnimalInfo.Tiger with tigerStr === AnimalInfo.Tiger.

AnimalInfo.Tiger is 'Tiger' since we assigned 'Tiger‘ to Tiger in AnimalInfo.

Conclusion

To compare enums in TypeScript, we can assign a value to each enum so we can compare them easily.

Sometimes, we want to attach to a stateless component’s ref in React.

In this article, we’ll look at how to attach to a stateless component’s ref in React.

How to attach to a stateless component’s ref in React?

To attach to a stateless component’s ref in React, we can use the useRef hook.

For instance, we write

const CustomTextInput = (props) => {
  const textInput = useRef();

  const handleClick = () => {
    textInput.current.focus();
  };

  return (
    <div>
      <input type="text" ref={textInput} />
      <input type="button" value="Focus the text input" onClick={handleClick} />
    </div>
  );
};

to create the textInput ref with the useRef hook,

Then we assign the set the ref prop’s value to textInput.

And then we can access the input element from textInput.current as we have in handleClick.

Conclusion

To attach to a stateless component’s ref in React, we can use the useRef hook.

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.