Author: John Au-Yeung

Sometimes, we want to round numbers with JavaScript parseFloat.

In this article, we’ll look at how to round numbers with JavaScript parseFloat.

How to round numbers with JavaScript parseFloat?

To round numbers with JavaScript parseFloat, we use the toFixed method.

For instance, we write

const rounded = parseFloat(num.toFixed(2));

to call toFixed on the num number with 2 to return a number string rounded to 2 decimal places.

Then we call parseFloat to convert the string to a number rounded to 2 decimal places.

Conclusion

To round numbers with JavaScript parseFloat, we use the toFixed method.

Sometimes, we want to trigger CSS animations in JavaScript.

In this article, we’ll look at how to trigger CSS animations in JavaScript.

How to trigger CSS animations in JavaScript?

To trigger CSS animations in JavaScript, we add keyframes for our animation.

For instance, we write

@keyframes spin1 {
  100% {
    transform: rotate(360deg);
  }
}
@keyframes spin2 {
  100% {
    transform: rotate(-360deg);
  }
}
@keyframes idle {
  100% {
  }
}

to add keyframes for the spin1, spin2, and idle animations.

Then we make our element animate by writing

document.getElementById("yourElement").style.animation =
  "spin2 4s linear infinite";

We select the element with getElementById.

Then we set its style.animation property to a string that has the animation name.

Conclusion

To trigger CSS animations in JavaScript, we add keyframes for our animation.

Sometimes, we want to do page redirect with successful ajax request with JavaScript.

In this article, we’ll look at how to do page redirect with successful ajax request with JavaScript.

How to do page redirect with successful ajax request with JavaScript?

To do page redirect with successful ajax request with JavaScript, we set location.href to the URL we want to redirect to.

For instance, we write

location.href = "http://www.example.com/ThankYou.html";

to set location.href to the URL we want to go to.

Conclusion

To do page redirect with successful ajax request with JavaScript, we set location.href to the URL we want to redirect to.

Sometimes, we want to write a Jest configuration file with JavaScript.

In this article, we’ll look at how to write a Jest configuration file with JavaScript.

How to write a Jest configuration file with JavaScript?

To write a Jest configuration file with JavaScript, we create a module with the config.

For instance, we write

{
  //...
  "scripts": {
    "start": "node server.js",
    "dev": "webpack-dev-server --hot --inline",
    "test": "jest --config ./jest-config.js",
    "build": "webpack",
    "postinstall": "webpack"
  }
  //...
}

to add the test script in package.json.

Then we write

module.exports = {
  verbose: true,
  setupTestFrameworkScriptFile: "./enzyme.js",
  roots: ["../__tests__"],
  modulePaths: ["./__stubs__"],
  moduleNameMapper: {
    ".scss$": "scss-stub.js",
  },
};

in jest-config.js to create a module with our Jest test config.

Conclusion

To write a Jest configuration file with JavaScript, we create a module with the config.

Sometimes, we want to install popper.js with JavaScript.

In this article, we’ll look at how to install popper.js with JavaScript.

How to install popper.js with JavaScript?

To install popper.js with JavaScript, we install it with NPM or Yarn.

For instance, we run

npm i popper.js

with NPM or

yarn add popper.js

with Yarn to install the popper.js package.

Conclusion

To install popper.js with JavaScript, we install it with NPM or Yarn.