Category: JavaScript

Sometimes, we want to convert day of year to a date in JavaScript.

In this article, we’ll look at how to convert day of year to a date in JavaScript.

How to convert day of year to a date in JavaScript?

To convert day of year to a date in JavaScript, we can call the Date constructor with the year and 9 for the rest of the arguments.

For instance, we write:

const dateFromDay = (year, day = 1) => {
  const date = new Date(year, 0);
  return new Date(date.setDate(day));
}
console.log(dateFromDay(2022, 1))

We create the dateFromDay function with the year and day parameters.

In the function, we instantiate the Date instance with year and 0 for month.

Then we call date.setDate with day which is set to 1 by default.

As a result, we see Sat Jan 01 2022 00:00:00 GMT-0800 (Pacific Standard Time) logged.

Conclusion

To convert day of year to a date in JavaScript, we can call the Date constructor with the year and 9 for the rest of the arguments.

Sometimes, we want to find the largest number from a string using a regular expression with JavaScript.

In this article, we’ll look at how to find the largest number from a string using a regular expression with JavaScript.

How to find the largest number from a string using a regular expression with JavaScript?

To find the largest number from a string using a regular expression with JavaScript, we can use the JavaScript string’s match method with the Math.max method.

For instance, we write:

const myString = "857nano620348splitted3412674relation5305743";
const largest = Math.max(...myString.match(/\d+/g));
console.log(largest)

We call myString.match with a regex to return all the numbers.

Then we call Math.max with all the returned number strings by using the spread operator to spread them as arguments.

As a result, largest is 5305743.

Conclusion

To find the largest number from a string using a regular expression with JavaScript, we can use the JavaScript string’s match method with the Math.max method.

Sometimes, we want to convert an element collection to an array in JavaScript.

In this article, we’ll look at how to convert an element collection to an array in JavaScript.

How to convert an element collection to an array in JavaScript?

To convert an element collection to an array in JavaScript, we can use the spread operator.

For instance, we write:

<div>

</div>
<div>

</div>

Then we write:

const divs = document.getElementsByTagName('div');
const myArray = [...divs];
console.log(myArray)

to select the divs with document.getElementsByTagName.

Then we spread the divs into an array with [...divs].

Now we see that myArray is an array of div elements.

Conclusion

To convert an element collection to an array in JavaScript, we can use the spread operator.

Sometimes, we want to store a function with jQuery data() method.

In this article, we’ll look at how to store a function with jQuery data() method.

How to store a function with jQuery data() method?

To store a function with jQuery data() method, we can create custom events and set our function as the event handler function.

For instance, we write:

<div id='foo'>

</div>

to add a div.

Then we write:

$('#foo').on('say', (e, arg) => {
  console.log('Foo says', arg);
});

$('#foo').trigger('say', 'hello');

to select the div with $('#foo').

Then we call on with the event name and event handler function respectively.

We get the value we triggered the event with from the arg parameter.

Then we trigger the event with the trigger function with the event name and data we want to send with our event.

Conclusion

To store a function with jQuery data() method, we can create custom events and set our function as the event handler function.

Sometimes, we want to write an if statement within a JavaScript object when setting an attribute.

In this article, we’ll look at how to write an if statement within a JavaScript object when setting an attribute.

How to write an if statement within a JavaScript object when setting an attribute?

To write an if statement within a JavaScript object when setting an attribute, we can use the ternary operator.

For instance, we write:

const testBoolean = true;

const object = {
  attributeOne: "attributeOne",
  attributeTwo: testBoolean ? "attributeTwo" : "attributeTwoToo"
}
console.log(object)

We set testBoolean to true.

And we set object.attributeTwi to 'attributeTwo' is testBoolean is true and 'attributeTwoToo' otherwise.

As a result, we see that object is {attributeOne: 'attributeOne', attributeTwo: 'attributeTwo'}.

Conclusion

To write an if statement within a JavaScript object when setting an attribute, we can use the ternary operator.