My experiments with codegolfing
Language Javascript , ES6 1. Days of a month in a non-leap year m=(n)=>(15662007>>(n-1)*2&3)|28
2. Repeating a string n number of times in O(log n) complexity
f=(s,n)=>n?['',s][n&1] + f(s+s,n>>1):''
3. Base 64 encoding (under progress)
b64=n=>{var hash = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'; return[...n].map(x=>'00000000'.slice(Math.ceil(Math.log2(x.charCodeAt(0)))) + x.charCodeAt(0).toString(2)).join('').match(/.{6}/g).map(x=>hash[parseInt(x,2)])}