Category: JavaScript Answers

Sometimes, we want to query MongoDB ObjectId by date with JavaScript.

In this article, we’ll look at how to query MongoDB ObjectId by date with JavaScript.

How to query MongoDB ObjectId by date with JavaScript?

To query MongoDB ObjectId by date with JavaScript, we call the ObjectId.fromDate method.

For instance, we write

db.users.find({
  _id: { $lt: ObjectId.fromDate(new ISODate("2022-01-05T00:00:00.000Z")) },
});

to call find to find the users entries that has object ID less than the given date.

We call ObjectId.fromDate to convert the ISODate to an object ID.

Conclusion

To query MongoDB ObjectId by date with JavaScript, we call the ObjectId.fromDate method.

Sometimes, we want to check for not null with JavaScript.

In this article, we’ll look at how to check for not null with JavaScript.

How to check for not null with JavaScript?

To check for not null with JavaScript, we can use the !== operator.

For instance, we write

if (val !== null) {
  //...
}

to check if val isn’t equal to null with

val !== null

Conclusion

To check for not null with JavaScript, we can use the !== operator.

Sometimes, we want to remove padding or margins from Google Charts and JavaScript.

In this article, we’ll look at how to remove padding or margins from Google Charts and JavaScript.

How to remove padding or margins from Google Charts and JavaScript?

To remove padding or margins from Google Charts and JavaScript, we can set the width and height options.

For instance, we write

const options = {
  title: "How Much I Ate Last Night",
  width: 350,
  height: 400,
  chartArea: { width: "100%", height: "80%" },
  legend: { position: "bottom" },
};

to set the width and height in pixels.

And then we set the chartArea to fill 100% of the width and height to remove the margins and padding.

Conclusion

To remove padding or margins from Google Charts and JavaScript, we can set the width and height options.

Sometimes, we want to modify a query string without reloading the page with JavaScript.

In this article, we’ll look at how to modify a query string without reloading the page with JavaScript.

How to modify a query string without reloading the page with JavaScript?

To modify a query string without reloading the page with JavaScript, we can use the history.pushState method.

For instance, we write

const newUrl =
  window.location.protocol +
  "//" +
  window.location.host +
  window.location.pathname +
  "?myNewUrlQuery=1";
window.history.pushState({ path: newUrl }, "", newUrl);

to create the newUrl URL string.

Then we call pushState with { path: newUrl } and newUrl to navigate to newUrl without reloading the page.

We get the current URL data from window.location.

We get the protocol with window.location.protocol.

host has the hostname.

pathname has the path before the query string.

Conclusion

To modify a query string without reloading the page with JavaScript, we can use the history.pushState method.

Sometimes, we want to add paste image from clipboard functionality with JavaScript.

In this article, we’ll look at how to add paste image from clipboard functionality with JavaScript.

How to add paste image from clipboard functionality with JavaScript?

To add paste image from clipboard functionality with JavaScript, we can listen to the document paste event and get the image from the paste event handler.

For instance, we write

document.onpaste = (event) => {
  const items = (event.clipboardData || event.originalEvent.clipboardData)
    .items;
  console.log(JSON.stringify(items));
  let blob = null;
  for (let i = 0; i < items.length; i++) {
    if (items[i].type.indexOf("image") === 0) {
      blob = items[i].getAsFile();
    }
  }

  if (blob !== null) {
    const reader = new FileReader();
    reader.onload = (event) =>{
      console.log(event.target.result); 
    };
    reader.readAsDataURL(blob);
  }
};

to set document.onpaste function to a function that gets the image data.

In it, we get the clipboard data with

const items = (event.clipboardData || event.originalEvent.clipboardData)
    .items;

Then we create the blob with a for loop that gets the item from the items array with type having the substring 'image' in it.

Then we use the FileReader object’s readAsDataURL to read the blob as a base64 image URL string.

And we get the image data with event.target.result in reader.onload.

Conclusion

To add paste image from clipboard functionality with JavaScript, we can listen to the document paste event and get the image from the paste event handler.