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Nov 19, 2022CodeCatch
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More JavaScript Posts

deep merge objects

Nov 19, 2022CodeCatch

0 likes • 3 views

const deepMerge = (a, b, fn) =>
[...new Set([...Object.keys(a), ...Object.keys(b)])].reduce(
(acc, key) => ({ ...acc, [key]: fn(key, a[key], b[key]) }),
{}
);
deepMerge(
{ a: true, b: { c: [1, 2, 3] } },
{ a: false, b: { d: [1, 2, 3] } },
(key, a, b) => (key === 'a' ? a && b : Object.assign({}, a, b))
);
// { a: false, b: { c: [ 1, 2, 3 ], d: [ 1, 2, 3 ] } }

Sequential Queue

Feb 6, 2021LeifMessinger

0 likes • 2 views

class SequentialQueue{ //if you want it to go backwards, too bad
next(){
return this.i++;
}
constructor(start = 0){
this.i = start;
}
}
const que = new SequentialQueue(0);
for(let i = 0; i < 10; i++){
console.log(que.next());
}

Longest Palindromic Substring

Nov 19, 2022CodeCatch

0 likes • 2 views

const longestPalindrome = (s) => {
if(s.length === 1) return s
const odd = longestOddPalindrome(s)
const even = longestEvenPalindrome(s)
if(odd.length >= even.length) return odd
if(even.length > odd.length) return even
};
const longestOddPalindrome = (s) => {
let longest = 0
let longestSubStr = ""
for(let i = 1; i < s.length; i++) {
let currentLongest = 1
let currentLongestSubStr = ""
let left = i - 1
let right = i + 1
while(left >= 0 && right < s.length) {
const leftLetter = s[left]
const rightLetter = s[right]
left--
right++
if(leftLetter === rightLetter) {
currentLongest += 2
currentLongestSubStr = s.slice(left+1, right)
} else break
}
if(currentLongest > longest) {
if(currentLongestSubStr) longestSubStr = currentLongestSubStr
else longestSubStr = s[i]
longest = currentLongest
}
}
return longestSubStr
}
const longestEvenPalindrome = (s) => {
let longest = 0
let longestSubStr = ""
for(let i = 0; i < s.length - 1; i++) {
if(s[i] !== s[i+1]) continue;
let currentLongest = 2
let currentLongestSubStr = ""
let left = i - 1
let right = i + 2
while(left >= 0 && right < s.length) {
const leftLetter = s[left]
const rightLetter = s[right]
left--
right++
if(leftLetter === rightLetter) {
currentLongest += 2
currentLongestSubStr = s.slice(left+1, right)
} else break
}
if(currentLongest > longest) {
if(currentLongestSubStr) longestSubStr = currentLongestSubStr
else longestSubStr = s[i] + s[i+1]
longest = currentLongest
}
}
return longestSubStr
}
console.log(longestPalindrome("babad"))

Invert Binary Tree

Oct 15, 2022CodeCatch

2 likes • 8 views

var invertTree = function(root) {
const reverseNode = node => {
if (node == null) {
return null
}
reverseNode(node.left);
reverseNode(node.right);
let holdLeft = node.left;
node.left = node.right;
node.right = holdLeft;
return node;
}
return reverseNode(root);
};

Composing components

Nov 19, 2022CodeCatch

0 likes • 3 views

function Welcome(props) {
return <h1>Hello, {props.name}</h1>;
}
function App() {
return (
<div>
<Welcome name="Sara" />
<Welcome name="Cahal" />
<Welcome name="Edite" />
</div>
);
}
ReactDOM.render(
<App />,
document.getElementById('root')
);

compact object

Nov 19, 2022CodeCatch

0 likes • 0 views

const compactObject = val => {
const data = Array.isArray(val) ? val.filter(Boolean) : val;
return Object.keys(data).reduce(
(acc, key) => {
const value = data[key];
if (Boolean(value))
acc[key] = typeof value === 'object' ? compactObject(value) : value;
return acc;
},
Array.isArray(val) ? [] : {}
);
};
const obj = {
a: null,
b: false,
c: true,
d: 0,
e: 1,
f: '',
g: 'a',
h: [null, false, '', true, 1, 'a'],
i: { j: 0, k: false, l: 'a' }
};
compactObject(obj);
// { c: true, e: 1, g: 'a', h: [ true, 1, 'a' ], i: { l: 'a' } }