compress a string

Question

Given a string, compress the repeating letters with count number

compress('a') // 'a'
compress('aa') // 'a2'
compress('aaa') // 'a3'
compress('aaab') // 'a3b'
compress('aaabb') // 'a3b2'
compress('aaabba') // 'a3b2a'

Code

/**
 * @param {string} str
 * @return {string}
 */
function compress(str) {
  // your code here
}

Source

Source From