Category: JavaScript Answers

Sometimes, we want to set multiple attributes for an element at once with JavaScript.

In this article, we’ll look at how to set multiple attributes for an element at once with JavaScript.

How to set multiple attributes for an element at once with JavaScript?

To set multiple attributes for an element at once with JavaScript, we can call the element’s setAttribute method.

For instance, we write

const setAttributes = (el, attrs) => {
  for (const [key, val] of Object.entries(attrs)) {
    el.setAttribute(key, val);
  }
};

const attrs = {
  src: "http://example.com/something.jpeg",
  height: "100%",
  //...
};
setAttributes(elem, attrs);

to define the setAttributes function.

In it, we use a for-of loop to loop through each property that we get from Object.entries.

In the loop, we call el.setAttribute with key and val to set attribute with name key to val.

Then we call setAttributes with the elem element and the attrs object with the attributes we want to set.

Conclusion

To set multiple attributes for an element at once with JavaScript, we can call the element’s setAttribute method.

Sometimes, we want to loop through localStorage in HTML5 and JavaScript.

In this article, we’ll look at how to loop through localStorage in HTML5 and JavaScript.

How to loop through localStorage in HTML5 and JavaScript?

To loop through localStorage in HTML5 and JavaScript,. we can use the Object.keys method to get the keys in localStorage.

For instance, we write

Object.keys(localStorage).forEach((key) => {
  console.log(localStorage.getItem(key));
});

to call Object.keys with localStorage to get an array of keys in localStorage.

Then we call forEach with a callback to get the value with the given key with getItem.

Conclusion

To loop through localStorage in HTML5 and JavaScript,. we can use the Object.keys method to get the keys in localStorage.

Sometimes, we want to truncate decimal numbers in JavaScript.

In this article, we’ll look at how to truncate decimal numbers in JavaScript.

How to truncate decimal numbers in JavaScript?

To truncate decimal numbers in JavaScript, we can use the Math.trunc method.

For instance, we write

const a = 5.467;
const truncated = Math.trunc(a * 100) / 100;

to call Math.trunc with the number a multiplied by 100 to truncate the number.

Then we divide the truncated number by 100 to return a truncated to 2 decimal places.

Conclusion

To truncate decimal numbers in JavaScript, we can use the Math.trunc method.

Sometimes, we want to convert seconds to HH:mm:ss in moment.js and JavaScript.

In this article, we’ll look at how to convert seconds to HH:mm:ss in moment.js and JavaScript.

How to convert seconds to HH:mm:ss in moment.js and JavaScript?

To convert seconds to HH:mm:ss in moment.js and JavaScript, we can use the format method.

For instance, we write

const secs = 456;

const formatted = moment.utc(secs * 1000).format("HH:mm:ss");

console.log(formatted);

to call moment.utc with the sec seconds converted to milliseconds to create a moment object with the milliseconds.

Then we call format with "HH:mm:ss" to convert the milliseconds to a string in HH:mm:ss format.

Conclusion

To convert seconds to HH:mm:ss in moment.js and JavaScript, we can use the format method.

Sometimes, we want to get image dimensions with JavaScript.

In this article, we’ll look at how to get image dimensions with JavaScript.

How to get image dimensions with JavaScript?

To get image dimensions with JavaScript, we can use the width and height properties.

For instance, we write

const img = new Image();

img.onload = () => {
  const height = img.height;
  const width = img.width;
  //...
};

img.src = url;

to create an img element with the Image constructor.

Then we get the height and width of the img image in the img.onload method, which runs when the image is loaded.

Then we load the image by setting img.src to the url of the image.

Conclusion

To get image dimensions with JavaScript, we can use the width and height properties.