Category: JavaScript Answers

Sometimes, we want to define a JavaScript function to convert color names to hex codes.

In this article, we’ll look at how to define a JavaScript function to convert color names to hex codes.

How to define a JavaScript function to convert color names to hex codes?

To define a JavaScript function to convert color names to hex codes, we can use the canvas.

For instance, we write

const standardizeColor = (str) => {
  const ctx = document.createElement("canvas").getContext("2d");
  ctx.fillStyle = str;
  return ctx.fillStyle;
};

to define the standardizeColor function.

In it, we create a canvas element with createElement.

And then we get its context with getContext.

Then we set its fillStyle to str.

And then we return the fillStyle value as a hex string.

Conclusion

To define JavaScript function to convert color names to hex codes, we can use the canvas.

Sometimes, we want to remove undefined values from an array with JavaScript.

In this article, we’ll look at how to remove undefined values from an array with JavaScript.

How to remove undefined values from an array with JavaScript?

To remove undefined values from an array with JavaScript, we can use the array filter method.

For instance, we write

let data = [42, 21, undefined, 50, 40, undefined, 9];
data = data.filter(Number);

to call data.filter with the Number function to return a new array without the undefined values in data.

Then we assign the new array back to data.

Conclusion

To remove undefined values from an array with JavaScript, we can use the array filter method.

Sometimes, we want to create a password generator with JavaScript.

In this article, we’ll look at how to create a password generator with JavaScript.

How to create a password generator with JavaScript?

To create a password generator with JavaScript, we can get random characters from a string.

For instance, we write

const generatePassword = () => {
  const length = 8;
  const charset =
    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
  const retVal = "";
  for (let i = 0, n = charset.length; i < length; ++i) {
    retVal += charset.charAt(Math.floor(Math.random() * n));
  }
  return retVal;
};

to define the generatePassword function.

In it, we loop i from 0 to length - 1 with a for loop.

In the loop, we get a random character from the charset string with

charset.charAt(Math.floor(Math.random() * n))

We use Math.floor(Math.random() * n) to get a random number between 0 and charset.length.

And we append the selected character to the retVal string.

Then we return the string after the loop is done.

Conclusion

To create a password generator with JavaScript, we can get random characters from a string.

Sometimes, we want to test part of object using Jest and JavaScript.

In this article, we’ll look at how to test part of object using Jest and JavaScript.

How to test part of object using Jest and JavaScript?

To test part of object using Jest and JavaScript, we can use the toMatchObject method.

For instance, we write

expect(parseTime("12:54")).toMatchObject({ hours: 12, minutes: 54 });

to call toMatchObject to check that the object returned by parseTime("12:54") has { hours: 12, minutes: 54 } in it.

Conclusion

To test part of object using Jest and JavaScript, we can use the toMatchObject method.

Sometimes, we want to get object property name as a string with JavaScript.

In this article, we’ll look at how to get object property name as a string with JavaScript.

How to get object property name as a string with JavaScript?

To get object property name as a string with JavaScript, we call the Object.keys method.

For instance, we write

const person = { firstName: "John", lastName: "Smith", age: "30" };
const listPropertyNames = Object.keys(person);

to call Object.keys with the person to return an array of non-inherited string property keys.

Therefore, listPropertyNames is ['firstName', 'lastName', 'age'].

Conclusion

To get object property name as a string with JavaScript, we call the Object.keys method.