const alphabet = 'abcdefghijklmnopqrstuvwxyz'.split('')
console.log(alphabet);
// outputs: ['a', 'b', 'c', ... 'z']Create an array of the alphabet.
Splitting a string with an empty string results in each character being placed into a slot in the new array.
const isTag = tag => {
return !/Unknown/.test(document.createElement(tag) + '')
}console.log('section:', isTag('section'))
console.log('div:', isTag('div'))
console.log('nav:', isTag('nav'))
console.log('banana:', isTag('banana'))
Check if a tagName is a valid html element.
When casting a dom node to a string, you’ll get a class name like this:
document.createElement('div') + ''
// '[object HTMLDivElement]'// you can cast to a string with `toString` if // you want things to be more readabledocument.createElement('section').toString()
// '[object HTMLElement]'document.createElement('input') + ''
// '[object HTMLInputElement]'When you try to create something with an unknown tagName you’ll end up with:
document.createElement('banana') + ''
// '[object HTMLUnknownElement]'So, testing for the presence of the string Unknown is an easy way to check if a tagName is valid in a given browser. This is the perfect kind of thing to memoize:
const tags = {}
const isTag = tag => {
if (tags[tag] != null) {
// already calculatedconsole.log('loking up: ', tag, tags[tag]);
return tags[tag]
}const result = !/Unknown/.test(document.createElement(tag) + '')
tags[tag] = result
return result}console.log('calculator', isTag('calculator'))
console.log('calculator', isTag('calculator'))
console.log('strong', isTag('strong'))
console.log('strong', isTag('strong'))
console.log(+new Date());
console.log(Date.now());
At some point I got in the habit of doing +new Date(). Not entirely sure why, Date.now() is the clear choice. I guess maybe Date.now() is newer…
confirmed… it is new, doesn’t work in much older browsers…
const collection = [
{ name: 'Joe' },
{ age: 31 },
{ job: 'programmer' }
];
const merged = Object.assign({}, ...collection);
console.log(merged);
Combine (“assign”) entire array of objects.
Saw this here… figured it was worth a quick post.
Object.assign(Number.prototype, {
*[Symbol.iterator]() {
for (let i = this; i--;)
yield this - i;
}});
console.log([...3]);
I saw this on twitter a little while back. Tweet was from James Padolsey. A fun trick, the thread is pretty entertaining.