Category: JavaScript Answers

Sometimes, we want to find and remove objects in an array based on a key value in JavaScript.

In this article, we’ll look at how to find and remove objects in an array based on a key value in JavaScript.

How to find and remove objects in an array based on a key value in JavaScript?

To find and remove objects in an array based on a key value in JavaScript, we can use the filter method.

For instance, we write

const newArray = myArray.filter((obj) => {
  return obj.id !== id;
});

to call myArray.filter with a callback to return all the items with obj.id not equal to id.

obj is the object is being processed in myArray.

Conclusion

To find and remove objects in an array based on a key value in JavaScript, we can use the filter method.

Sometimes, we want to parse date without time zone with JavaScript.

In this article, we’ll look at how to parse date without time zone with JavaScript.

How to parse date without time zone with JavaScript?

To parse date without time zone with JavaScript, we can add the time zone offset to the date without time zone.

For instance, we write

const date = new Date("2022-08-25T00:00:00");
const userTimezoneOffset = date.getTimezoneOffset() * 60000;
const d = new Date(date.getTime() - userTimezoneOffset);

to create a date object in UTC.

Then we call date.getTimezoneOffset to get the time zone offset in hours.

Then we multiply that by 60000 to get the offset in milliseconds.

Next, we call getTime to get the timestamp of date in milliseconds and then subtract that by userTimezoneOffset to get the date d that is in the local time zone.

Conclusion

To parse date without time zone with JavaScript, we can add the time zone offset to the date without time zone.

Sometimes, we want to reset setTimeout with JavaScript.

In this article, we’ll look at how to reset setTimeout with JavaScript.

How to reset setTimeout with JavaScript?

To reset setTimeout with JavaScript, we can call the clearTimeout function.

For instance, we write

const myTimer = setTimeout(() => {
  //...
}, 115000);

//...

clearTimeout(myTimer);

to call setTimeout to return a timer ID number and run the function after 115000 milliseconds.

Then we call clearTimeout with myTimer to stop the timer.

Conclusion

To reset setTimeout with JavaScript, we can call the clearTimeout function.

Sometimes, we want to scroll an iframe with JavaScript

In this article, we’ll look at how to scroll an iframe with JavaScript.

How to scroll an iframe with JavaScript?

To scroll an iframe with JavaScript, we can use the scrollTo method.

For instance, we write

const myIframe = document.getElementById("iframe");

myIframe.onload = () => {
  myIframe.contentWindow.scrollTo(xcoord, ycoord);
};

to get the iframe with getElementById.

Then we set its onload property to a function that scrolls itself to the x-y coordinates xcoord and ycoord with scrollTo.

We get the iframe window with myIframe.contentWindow.

Then we call scrollTo on the window.

Conclusion

To scroll an iframe with JavaScript, we can use the scrollTo method.

Sometimes, we want to format date to MM/dd/yyyy in JavaScript.

In this article, we’ll look at how to format date to MM/dd/yyyy in JavaScript.

How to format date to MM/dd/yyyy in JavaScript?

To format date to MM/dd/yyyy in JavaScript, we can use some date and string methods.

For instance, we write

const getFormattedDate = (date) => {
  let year = date.getFullYear();
  let month = (1 + date.getMonth()).toString().padStart(2, "0");
  let day = date.getDate().toString().padStart(2, "0");
  return month + "/" + day + "/" + year;
};

to create the getFormattedDate function.

In it, we get the 4 digit year from the date with getFullYear.

getMonth gets the month.

getDate gets the date of the month.

We call padStart to prepend 0 to pad the string to 2 digits if the number has less than 2 digits.

And then we return the month, day and year combined into a new string.

We add 1 to the month returned by getMonth to make it a human readable month number.

Conclusion

To format date to MM/dd/yyyy in JavaScript, we can use some date and string methods.