Author: John Au-Yeung

Sometimes, we want to use getElementsByClassName() with two classes with JavaScript.

In this article, we’ll look at how to use getElementsByClassName() with two classes with JavaScript.

How to use getElementsByClassName() with two classes with JavaScript?

To use getElementsByClassName() with two classes with JavaScript, we can use the querySelectorAll method.

For instance, we write

const els = document.querySelectorAll(".a,.b");

to call document.querySelectorAll to select all elements on the page with classes a and b.

We separate each class with commas in the selector.

Conclusion

To use getElementsByClassName() with two classes with JavaScript, we can use the querySelectorAll method.

Sometimes, we want to remove ‘&quot’ from JSON in JavaScript.

In this article, we’ll look at how to remove ‘&quot’ from JSON in JavaScript.

How to remove ‘&quot’ from JSON in JavaScript?

To remove ‘&quot’ from JSON in JavaScript, we call the string replace method.

For instance, we write

const obj = JSON.parse(data.replace(/"/g, '"'));

to call data.replace with /"/g and '"' to replace all instances of '&quot' with double quotes on the data string.

Then we call JSON.parse to parse the string returned by replace into the obj object.

Conclusion

To remove ‘&quot’ from JSON in JavaScript, we call the string replace method.

Sometimes, we want to compare arrays of objects in JavaScript.

In this article, we’ll look at how to compare arrays of objects in JavaScript.

How to compare arrays of objects in JavaScript?

To compare arrays of objects in JavaScript, we can use some array properties and methods.

For instance, we write

const obj1 = { name: "John", age: 33 };
const obj2 = { age: 33, name: "John" };
const obj3 = { name: "John", age: 45 };

const arr1 = [obj1, obj1];
const arr2 = [obj1, obj2];
const arr3 = [obj1, obj3];

const objectsEqual = (o1, o2) =>
  typeof o1 === "object" && Object.keys(o1).length > 0
    ? Object.keys(o1).length === Object.keys(o2).length &&
      Object.keys(o1).every((p) => objectsEqual(o1[p], o2[p]))
    : o1 === o2;

const arraysEqual = (a1, a2) =>
  a1.length === a2.length && a1.every((o, idx) => objectsEqual(o, a2[idx]));

console.log(arraysEqual(arr1, arr2)); // true
console.log(arraysEqual(arr1, arr3));

to define the objectsEqual function that recursive checks if every property in objects o1 and o2 are equal.

We do this by checking if o1 is an object.

If it is, then we check if the number of properties of o1 and o2 are the same with

Object.keys(o1).length === Object.keys(o2).length

And then we use

Object.keys(o1).every((p) => objectsEqual(o1[p], o2[p]))

to check if each property is equal.

We call objectsEqual with the property p of o1 and o2 since they’re objects.

Otherwise, we compare the values directly with

o1 === o2

Then we define the arrayEqual function that checks if array a1 and a2‘s length and content are equal with

a1.length === a2.length && a1.every((o, idx) => objectsEqual(o, a2[idx]);

Conclusion

To compare arrays of objects in JavaScript, we can use some array properties and methods.

Sometimes, we want to replace a regex capture group with uppercase in JavaScript.

In this article, we’ll look at how to replace a regex capture group with uppercase in JavaScript.

How to replace a regex capture group with uppercase in JavaScript?

To replace a regex capture group with uppercase in JavaScript, we call string replace with a callback.

For instance, we write

const r = a.replace(/(f)/, (v) => {
  return v.toUpperCase();
});

to call a string’s replace to find the capturing group with f inside.

And we replace the matches values with the value converted to upper case with toUpperCase.

Conclusion

To replace a regex capture group with uppercase in JavaScript, we call string replace with a callback.