Author: John Au-Yeung

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.

Sometimes, we want to programmatically force an onchange event on an input with JavaScript.

In this article, we’ll look at how to programmatically force an onchange event on an input with JavaScript.

How to programmatically force an onchange event on an input with JavaScript?

To programmatically force an onchange event on an input with JavaScript, we use the Event constructor.

For instance, we write

const element = document.getElementById("input");
const event = new Event("change");
element.dispatchEvent(event);

to call getElementById to select the input element.

Then we create a new Event object that triggers the change event.

And then we call element.dispatchEvent with event to trigger the change event.

Conclusion

To programmatically force an onchange event on an input with JavaScript, we use the Event constructor.

Sometimes, we want to convert hyphens to camel case with JavaScript.

In this article, we’ll look at how to convert hyphens to camel case with JavaScript.

How to convert hyphens to camel case with JavaScript?

To convert hyphens to camel case with JavaScript, we can use the string replace method.

For instance, we write

const camelCased = myString.replace(/-([a-z])/g, (g) => {
  return g[1].toUpperCase();
});

to call myString.replace with a regex that matches a letter before hyphen and a callback that returns the replacement for the match.

We use -([a-z]) to match a hyphen with a lower case letter after it.

And we use the g flag to return all matches.

Conclusion

To convert hyphens to camel case with JavaScript, we can use the string replace method.

Sometimes, we want to delete a query string parameter in JavaScript.

In this article, we’ll look at how to delete a query string parameter in JavaScript.

How to delete a query string parameter in JavaScript?

To delete a query string parameter in JavaScript, we can use the URLSearchParams constructor.

For instance, we write

const params = new URLSearchParams("param1=1&param2=2&param3=3");
console.log(params.toString());
params.delete("param2");
console.log(params.toString());

to pass in the query string into the URLSearchParams constructor.

Then we call delete on the params object to remove the query parameter with key 'param2'.

Then we convert the params object to a string with toString.

Conclusion

To delete a query string parameter in JavaScript, we can use the URLSearchParams constructor.