Category: JavaScript Answers

Sometimes, we want to check if mouse button down with JavaScript.

In this article, we’ll look at how to check if mouse button down with JavaScript.

How to check if mouse button down with JavaScript?

To check if mouse button down with JavaScript, we listen for the mousedown and mouseup events.

For instance, we write

let mouseDown = false;
document.body.onmousedown = () => {
  mouseDown = true;
};
document.body.onmouseup = () => {
  mouseDown = false;
};

if (mouseDown) {
  // ....
}

to listen for the mousedown event on the body element with

document.body.onmousedown = () => {
  mouseDown = true;
};

We set mouseDown to true in document.body.onmousedown since the mouse button is down.

Likewise, we listen to the mouseup event with

document.body.onmouseup = () => {
  mouseDown = false;
};

And we set mouseDown to false.

Then we do something is mouseDown is true with

if (mouseDown) {
  // ....
}

Conclusion

To check if mouse button down with JavaScript, we listen for the mousedown and mouseup events.

Sometimes, we want to run only one test with Cypress and JavaScript.

In this article, we’ll look at how to run only one test with Cypress and JavaScript.

How to run only one test with Cypress and JavaScript?

To run only one test with Cypress and JavaScript, we can set the --space option or use the it.only method.

For instance, we run

cypress run --spec path/to/file.spec.js

to run the tests in path/to/file.spec.js.

In our test, we write

it.only("only run this one", () => {
  // ...
});

it("not this one", () => {});

to run only the first test by calling creating the test with it.only.

Conclusion

To run only one test with Cypress and JavaScript, we can set the --space option or use the it.only method.

Sometimes, we want to share variables between files in Node.js.

In this article, we’ll look at how to share variables between files in Node.js.

How to share variables between files in Node.js?

To share variables between files in Node.js, we export the variables and then import them where we want to use them.

For instance, we write

module.js

const name = "foobar";

exports.name = name;

to export the name variable with

exports.name = name;

Then we import module.js and use name in main.js with

const myModule = require("./module");

const name = myModule.name;

Conclusion

To share variables between files in Node.js, we export the variables and then import them where we want to use them.

Sometimes, we want to submit a form using PhantomJS and JavaScript.

In this article, we’ll look at how to submit a form using PhantomJS and JavaScript.

How to submit a form using PhantomJS and JavaScript?

To submit a form using PhantomJS and JavaScript, we use CasperJS.

To install it, we run

npm install casperjs

after installing PhantomJS.

Then we use it by writing

const casper = require("casper").create();

casper.start("http://example.com/login", function () {
  this.fill(
    "form#loginForm",
    {
      login: "admin",
      password: "12345678",
    },
    true
  );
  this.evaluate(() => {
    document.querySelector('input[type="submit"]').click();
  });
});

We call casper.start to open the page at the given URL.

And we call it with a function that calls this.fill to get the form with the "form#loginForm" selector.

And we send the values of the fields with the names as the keys with the values in the values.

Next, we call this.evaluate with a callback that clicks the button after we filled the form.

Conclusion

To submit a form using PhantomJS and JavaScript, we use CasperJS.

Sometimes, we want to remove the string on the beginning of an URL with JavaScript.

In this article, we’ll look at how to remove the string on the beginning of an URL with JavaScript.

How to remove the string on the beginning of an URL with JavaScript?

To remove the string on the beginning of an URL with JavaScript, we can use the string replace method.

For instance, we write

const s = "www.testwww.com".replace("www.", "");

to call replace with 'www.' and '' to replace 'www.' with an empty string to return a string without 'www.' at the beginning.

Conclusion

To remove the string on the beginning of an URL with JavaScript, we can use the string replace method.