Category: JavaScript Answers

Sometimes, we want to define multiple variables on a single line with JavaScript.

In this article, we’ll look at how to define multiple variables on a single line with JavaScript.

How to define multiple variables on a single line with JavaScript?

To define multiple variables on a single line with JavaScript, we can use the array destructuring syntax.

For instance, we write

const [a, b, c, d] = [0, 1, 2, 3];

to assign a to 0, b to 1, cto 2, andd` to 3 with the array destructuring syntax.

Conclusion

To define multiple variables on a single line with JavaScript, we can use the array destructuring syntax.

Sometimes, we want to convert a Firestore date or timestamp to a JavaScript Date.

In this article, we’ll look at how to convert a Firestore date or timestamp to a JavaScript Date.

How to convert a Firestore date or timestamp to a JavaScript Date?

To convert a Firestore date or timestamp to a JavaScript Date, we use firebase.firestore.Timestamp.fromDate to convert the a date to a Firestore timestamp.

We call toDate on the timestamp object to convert it back to a JavaScript date.

For instance, we write

const t = firebase.firestore.Timestamp.fromDate(new Date());
const d = t.toDate();

to call firebase.firestore.Timestamp.fromDate with a JavaScript date object to convert it to a Firebase timestamp object.

Then we call toDate on the t timestamp object to convert it back to a JavaScript date.

Conclusion

To convert a Firestore date or timestamp to a JavaScript Date, we use firebase.firestore.Timestamp.fromDate to convert the a date to a Firestore timestamp.

We call toDate on the timestamp object to convert it back to a JavaScript date.

Sometimes, we want to disable an input type=text with JavaScript.

In this article, we’ll look at how to disable an input type=text with JavaScript.

How to disable an input type=text with JavaScript?

To disable an input type=text with JavaScript, we set the disabled property of the input to true.

For instance, we write

document.getElementById("foo").disabled = true;

to select the input with getElementById.

Then we set its disabled property to true to add the disabled attribute on the input.

Likewise, we write

document.getElementById("foo").readOnly = true;

to set the readOnly property to true to add the readonly attribute to the input.

Conclusion

To disable an input type=text with JavaScript, we set the disabled property of the input to true.

Sometimes, we want to print a list of all installed Node.js modules.

In this article, we’ll look at how to print a list of all installed Node.js modules.

How to print a list of all installed Node.js modules?

To print a list of all installed Node.js modules, we run npm ls.

To list all globally installed modules, we run

npm -g ls --depth=0

And to list all locally installed modules in a folder, we run

npm ls --depth=0

in the project folder.

Conclusion

To print a list of all installed Node.js modules, we run npm ls.

Sometimes, we want to count text lines inside an DOM element with JavaScript.

In this article, we’ll look at how to count text lines inside an DOM element with JavaScript.

How to count text lines inside an DOM element with JavaScript?

To count text lines inside an DOM element with JavaScript, we can divide the element height by its line height.

For instance, we write

const el = document.getElementById("content");
const divHeight = el.offsetHeight;
const lineHeight = parseInt(el.style.lineHeight);
const lines = divHeight / lineHeight;

to select the div with getElementById.

Then we get the div’s height with offsetHeight.

And then we get the lineHeight from the div.

Finally, we get number of lines of text by dividing divHeight and lineHeight.

Conclusion

To count text lines inside an DOM element with JavaScript, we can divide the element height by its line height.