如何在javascript中计算字符串的每个连续唯一字符的数量

Question

How to count the number of each consecutive unique character of a string.

Case exampe:
    // Function Name    : CountUniqueChar()
    // Input        : String
    // Output       : Array Object [{k: v}]
    
    // Example : 
    // Input    : “aaaasssiia”
    // output : [{“a”: 4}, {“s”: 3}, {“i”: 2}, {“a”: 1}]

Answer 1

Using matchAll() with a regular expression and map() :

 const count = (s) => [...s.matchAll(/(.)\\1*/g)].map(([{length}, c]) => ({[c]: length})); console.log(count('aaaasssiia'));

Answer 2

You can simple achieve this using match and map using /(\\w)\\1*/g

 const str = "aaaasssiia"; const result = str.match(/(\\w)\\1*/g).map((s) => ({ [s[0]]: s.length })); console.log(result);

Answer 3

Use for loop to iterate over each character in a string and compare with next character to keep count of consecutive unique char.

 const input = "aaaasssiia"; const countChar = (str) => { const list = []; let count = 1; for (let i = 0; i < str.length; i++) { if (str[i] === str[i + 1]) { count++ } else { const obj = {}; obj[str[i]] = count; list.push(obj); count = 1; } } return list; } console.log(countChar(input))