Category: JavaScript

Sometimes, we want to iterate through an existing array and add the items to a new array in Node.js and JavaScript.

In this article, we’ll look at how to iterate through an existing array and add the items to a new array in Node.js and JavaScript.

How to iterate through an existing array and add the items to a new array in Node.js and JavaScript?

To iterate through an existing array and add the items to a new array in Node.js and JavaScript, we call the array map method.

For instance, we write

const array = calendars.map((item) => item.id);
console.log(array);

to call calendars.map with a callback to return the id property value of each item in the calendars array.

Then we put the values into a new array and return it.

Conclusion

To iterate through an existing array and add the items to a new array in Node.js and JavaScript, we call the array map method.

Sometimes, we want to fix getBounds is undefined with Google Maps API v3 and JavaScript.

In this article, we’ll look at how to fix getBounds is undefined with Google Maps API v3 and JavaScript.

How to fix getBounds is undefined with Google Maps API v3 and JavaScript?

To fix getBounds is undefined with Google Maps API v3 and JavaScript, we can use the map.

For instance, we write

const map = new google.maps.Map(document.getElementById("map"), {
  zoom: 12,
  center: new google.maps.LatLng(55.755327, 37.622166),
  mapTypeId: google.maps.MapTypeId.ROADMAP,
});

google.maps.event.addListener(map, "bounds_changed", () => {
  console.log(map.getBounds());
});

to create a map with the google.maps.Map constructor.

We set the zoom, center, and the map type by setting mapTypeId.

Then we call addListener to listen for the bounds_changed event on the map.

And we get the bounds with map.getBounds in the bounds_changed event listener.

Conclusion

To fix getBounds is undefined with Google Maps API v3 and JavaScript, we can use the map.

Sometimes, we want to get the text from a dropdown box with JavaScript.

in this article, we’ll look at how to get the text from a dropdown box with JavaScript.

How to get the text from a dropdown box with JavaScript?

To get the text from a dropdown box with JavaScript, we can use the options and selectedIndex properties.

For instance, we write

const skillsSelect = document.getElementById("newSkill");
const selectedText = skillsSelect.options[skillsSelect.selectedIndex].text;

to select the select element with getElementById.

Then we use skillsSelect.options to get all the options in an iterable object.

We use skillsSelect.selectedIndex to get the index of the selected option and use that to get the selected option with skillsSelect.options[skillsSelect.selectedIndex].

Then we use the text property to get the text of the dropdown.

Conclusion

To get the text from a dropdown box with JavaScript, we can use the options and selectedIndex properties.

Sometimes, we want to validate URL using JavaScript.

In this article, we’ll look at how to validate URL using JavaScript.

How to validate URL using JavaScript?

To validate URL using JavaScript, we can use a regex.

For instance, we write

const validateURL = (textVal) => {
  const urlRegex =
    /(^|\s)((https?:\/\/)?[\w-]+(\.[\w-]+)+\.?(:\d+)?(\/\S*)?)/gi;
  return urlRegex.test(textVal);
};

to define the validateURL function.

In it, we define the urlRegex that matches URLs.

We use (^|\s)((https?:\/\/)?[\w-]+ to match the protocol, colon, and the slashes.

Then the rest of the regex matches the rest of the URL.

g checks for all matches.

And i makes the regex match in a case insensitive manner.

Then we call urlRegex.test to check if textVal is a URL string.

Conclusion

To validate URL using JavaScript, we can use a regex.

Sometimes, we want to remove key and value from hash in JavaScript.

In this article, we’ll look at how to remove key and value from hash in JavaScript.

How to remove key and value from hash in JavaScript?

To remove key and value from hash in JavaScript, we use the delete operator.

For instance, we write

const myHash = {};
myHash["key1"] = { Name: "Object 1" };
myhash["key2"] = null;
myHash["key3"] = { Name: "Object 3" };

delete myHash["key2"];

to create the myHash object.

Then we add some properties to it.

We then remove the key2 property from myHash with

delete myHash["key2"];

Conclusion

To remove key and value from hash in JavaScript, we use the delete operator.