Category: JavaScript

Sometimes, we want to add a day to a date in TypeScript.

In this article, we’ll look at how to add a day to a date in TypeScript.

How to add a day to a date in TypeScript?

To add a day to a date in TypeScript, we can call the getDate and setDate methods.

For instance, we write

const addDays = (date: Date, days: number): Date => {
  date.setDate(date.getDate() + days);
  return date;
};

to define the addDays function that takes the number of days to add to the date.

We get the date of date with getDate.

Then we add days to the date returned by getDate and use the sum as the argument of setDate to add the days to date.

And then we return date.

Conclusion

To add a day to a date in TypeScript, we can call the getDate and setDate methods.

Sometimes, we want to add the colSpan attribute in React.

In this article, we’ll look at how to add the colSpan attribute in React.

How to add the colSpan attribute in React?

To add the colSpan attribute in React, we can add the colSpan prop.

For instance, we write

<th colSpan={2}>{this.props.category}</th>;

to add the colSpan prop in a th element to set the colspan to 2.

Conclusion

To add the colSpan attribute in React, we can add the colSpan prop.

Sometimes, we want to get the difference between two arrays with TypeScript.

In this article, we’ll look at how to get the difference between two arrays with TypeScript.

How to get the difference between two arrays with TypeScript?

To get the difference between two arrays with TypeScript, we use the array filter and indexOf methods.

For instance, we write

const a1 = ["a", "b", "c", "d", "e", "f", "g"];
const a2 = ["a", "b", "c", "d", "z"];

const missing = a1.filter((item) => a2.indexOf(item) < 0);
console.log(missing);

to get the items in a1 that aren’t in a2 and return the list of items as an array.

To do this, we call a1.filter with a callback that checks if each item in a1 isn’t in a2 with a2.indexOf(item) < 0.

Then missing would have the items in a1 that aren’t in a2 in an array.

Conclusion

To get the difference between two arrays with TypeScript, we use the array filter and indexOf methods.

Sometimes, we want to add types of Axios mock using Jest and TypeScript.

In this article, we’ll look at how to add types of Axios mock using Jest and TypeScript.

How to add types of Axios mock using Jest and TypeScript?

To add types of Axios mock using Jest and TypeScript, we add the jest.Mocked<typeof axios> type.

For instance, we write

import axios from "axios";
jest.mock("axios");
const mockedAxios = axios as jest.Mocked<typeof axios>;

to get the type of axios with typeof axios.

Then we get the type for the mocked version of axios by wrapping jest.Mocked<> around it.

Conclusion

To add types of Axios mock using Jest and TypeScript, we add the jest.Mocked<typeof axios> type.

Sometimes, we want to add left padding to a string with zeros with TypeScript.

In this article, we’ll look at how to add left padding to a string with zeros with TypeScript.

How to add left padding to a string with zeros with TypeScript?

To add left padding to a string with zeros with TypeScript, we can use the string padStart method.

For instance, we write

const s: string = str.padStart(9, "0");

to prepend the str string with 0’s until the length of it is 9.

Conclusion

To add left padding to a string with zeros with TypeScript, we can use the string padStart method.