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JavaScript Answers

How to create the checkbox dynamically using JavaScript?

To create the checkbox dynamically using JavaScript, we use the createElement method.

For instance, we write

const checkbox = document.createElement("input");
checkbox.type = "checkbox";
checkbox.name = "name";
checkbox.value = "value";
checkbox.id = "id";

to create an input element with createElement.

We set its type attribute to 'checkbox' to make it a checkbox by setting the type property.

Then we set its name, value and id attributes by setting the properties with the same name.

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JavaScript Answers

How to define a regular expression for not allowing spaces in the input field with JavaScript?

To define a regular expression for not allowing spaces in the input field with JavaScript, we use the \S pattern.

For instance, we write

const regex = /^\S*$/;

to define a regex that matches any non-space characters with the \S+ pattern.

And we use ^ to match the start of a string and $ the end of a string.

We use * to match repetition.

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React Answers

How to detect browser in React?

To detect browser in React, we use the react-device-detect package.

To install it, we run

npm i react-device-detect

Then we use it by writing

import { isMobile } from "react-device-detect";

function App() {
  if (isMobile) {
    return <div> This content is available only on mobile</div>;
  }
  return <div> ...content </div>;
}

to use the isMobile variable to check if the content is displayed in the mobile browser.

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JavaScript Answers

How to get formatted date time in YYYY-MM-DD HH:mm:ss format using JavaScript?

To get formatted date time in YYYY-MM-DD HH:mm:ss format using JavaScript, we can use some date methods.

For instance, we write

const getFormattedDate = () => {
  const date = new Date();
  const str =
    date.getFullYear() +
    "-" +
    (date.getMonth() + 1) +
    "-" +
    date.getDate() +
    " " +
    date.getHours() +
    ":" +
    date.getMinutes() +
    ":" +
    date.getSeconds();
  return str;
};

to call getFullYear to get the 4 digit year.

We call getMonth to get the month and add 1 to get the human readable month.

We call getDate to get the date.

We call getHours to get the hours.

We call getMinutes to get the minutes.

And we call getSeconds to get the seconds.

Then we concatenate the values together to return the formatted date.

Categories
React Answers

How to mock the window size changing for a React component test with JavaScript?

To mock the window size changing for a React component test with JavaScript, we can mock the window.screen.width property.

For instance, we write

jest.spyOn(window.screen, "width", "get").mockReturnValue(1000);

to call jest.spyOn to mock the window.screen.width getter property.

And we call mockReturnValue to set its return value to 1000.