Author: John Au-Yeung

Web developer specializing in React, Vue, and front end development.

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Python Answers

How to get the return value of JavaScript code in Python Selenium?

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Sometimes, we want to get the return value of JavaScript code in Python Selenium.

In this article, we’ll look at how to get the return value of JavaScript code in Python Selenium.

How to get the return value of JavaScript code in Python Selenium?

To get the return value of JavaScript code in Python Selenium, we get the return value of the execute_script method.

For instance, we write

from selenium import webdriver

wd = webdriver.Firefox()
wd.get("http://localhost/foo/bar")
val = wd.execute_script("return 5")

to call execute_script to run the "return 5" JavaScript code.

Then we get the returned value from val, which is assigned the return value of execute_script.

Therefore, val is 5.

Conclusion

To get the return value of JavaScript code in Python Selenium, we get the return value of the execute_script method.

Categories
JavaScript Answers

How to determine if a div is scrolled to the bottom with JavaScript?

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Sometimes, we want to determine if a div is scrolled to the bottom with JavaScript.

In this article, we’ll look at how to determine if a div is scrolled to the bottom with JavaScript.

How to determine if a div is scrolled to the bottom with JavaScript?

To determine if a div is scrolled to the bottom with JavaScript, we check if scrollTop is the same as scrollHeight - offsetHeight.

For instance, we write

if (obj.scrollTop === obj.scrollHeight - obj.offsetHeight) {
}

to check if obj.scrollTop is equal to obj.scrollHeight - obj.offsetHeight.

If it is, then we scrolled to the bottom of the obj element.

Conclusion

To determine if a div is scrolled to the bottom with JavaScript, we check if scrollTop is the same as scrollHeight - offsetHeight.

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JavaScript Answers

How to load an image to a img element from a file input with JavaScript?

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Sometimes, we want to load an image to a img element from a file input with JavaScript.

In this article, we’ll look at how to load an image to a img element from a file input with JavaScript.

How to load an image to a img element from a file input with JavaScript?

To load an image to a img element from a file input with JavaScript, we can use the FileReader constructor.

For instance, we write

<input type="file" />
<img id="myimage" height="200" />

to add the file input and the img element.

Then we write

const input = document.querySelector("input");

input.onchange = (event) => {
  const selectedFile = event.target.files[0];
  const reader = new FileReader();

  const imgtag = document.getElementById("myimage");
  imgtag.title = selectedFile.name;

  reader.onload = (event) => {
    imgtag.src = event.target.result;
  };

  reader.readAsDataURL(selectedFile);
};

to select the file input with querySelector.

And then we set its onchange property to a function that runs when we change file selection.

We get the first selected file with event.target.files[0].

Then we create a FileReader object and call readAsDataURL on it with the selectedFile as its argument.

When the file is read, read.onload runs.

In it, we set the imgtag.src property to event.target.result, which the base64 URL string with the image data.

We set imgtag to the img element that we selected with getElementById.

Conclusion

To load an image to a img element from a file input with JavaScript, we can use the FileReader constructor.

Categories
HTML

How to add tooltips for cells in HTML table?

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Sometimes, we want to add tooltips for cells in HTML table.

In this article, we’ll look at how to add tooltips for cells in HTML table.

How to add tooltips for cells in HTML table?

To add tooltips for cells in HTML table, we add the title attribute to our table elements.

For instance, we write

<td title="This is Title">...</td>

to set the title attribute to the tooltip text in the td element.

Then when we hover the cell, the tooltip text would be the title attribute value.

Conclusion

To add tooltips for cells in HTML table, we add the title attribute to our table elements.

Categories
JavaScript Answers

How to convert ISO date to milliseconds in JavaScript?

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Sometimes, we want to convert ISO date to milliseconds in JavaScript.

In this article, we’ll look at how to convert ISO date to milliseconds in JavaScript.

How to convert ISO date to milliseconds in JavaScript?

To convert ISO date to milliseconds in JavaScript, we can use the date’s getTime method.

For instance, we write

const date = new Date("11/21/1987 16:00:00");
const milliseconds = date.getTime();
console.log(milliseconds);

to create a Date object.

Then we call getTime on it to get the timestamp in milliseconds.

Conclusion

To convert ISO date to milliseconds in JavaScript, we can use the date’s getTime method.