The cards don't have new lines in the code and it makes it very hard to read them. Any ideas on how a new line can be added.

Perhaps this should be added to the documentation. I shall try to solve it if there is no readily available answer.

I can create a pull request if an answer is provided.

From react docs

Note:
We recommend using React Testing Library which is designed to enable and encourage writing tests that use your components as the end users do.
Alternatively, Airbnb has released a testing utility called Enzyme, which makes it easy to assert, manipulate, and traverse your React Components’ output.

https://github.com/trekhleb/javascript-algorithms/blob/master/src/algorithms/sets/cartesian-product/cartesianProduct.js#L8

I think it makes more sense to return an empty array

// invalid input return null or throw an error
if (!setA || !setB) {
    return null;
}
if (!setA.length || !setB.length) {
    return []; 
}
// or do nothing since the for loop will not trigger anyway

A minor shortcoming of the structure of the OSSU CS crepository is that we are basically using one big page for the entire curriculum, and all secondary resources have to go in extras. This means that valuable secondary materials are kept separate from the primary resources that we recommend unless we add a footnote. It also discourages us from adding more narrative to the curriculum to explain wh

给定两个由小写字母构成的字符串 A 和 B ，只要我们可以通过交换 A 中的两个字母得到与 B 相等的结果，就返回 true ；否则返回 false 。

示例 1：

输入： A = "ab", B = "ba"
输出： true
示例 2：

输入： A = "ab", B = "ab"
输出： false
示例 3:

输入： A = "aa", B = "aa"
输出： true
示例 4：

输入： A = "aaaaaaabc", B = "aaaaaaacb"
输出： true
示例 5：

输入： A = "", B = "aa"
输出： false
 

提示：

0 <= A.length <= 20000
0 <= B.length <= 20000
A 和 B 仅由小写字母构成。

来源：力扣（L

Currently all the books are loaded when the homepage is loaded. Instead of this implement an infinite scroll that loads more books only when the user scrolls to the bottom of page.

See https://github.com/hackerkid/Mind-Expanding-Books/tree/master/app to setup development environment

Some possible suggestions are - sites which teach algorithms, sites which interactively visualize different algorithms. Also, notebooks/question pages of ACM themed contests can be added.

https://github.com/benoitvallon/computer-science-in-javascript/blob/master/data-structures-in-javascript/tree.es6.js#L33

Splice in the for loop shifts the elements in the array and skips the sibling of the node that was removed.

Fix PR:

You can test with:

const tree = new Tree();
tree.add('ceo');
tree.add('cto1', 'ceo');
tree.add('cto2', 'ceo');
tree.add('cto3', 'ceo');
tree