正则表达式能否写出粘连匹配（不使用es6的y）？

Question

var str="abc"; 
var patt1=/\w/g;
document.write(str.match(patt1));

以上代码中，匹配结果为 ['a','b','c']

请问有没有一种正则写法，可以使匹配结果为 ['a','ab','abc','b','bc','c'] ,类似于高中数学的组合

Answer 1

直接用组合算法吧~

python3

import itertools as itrs

s = "abc"
rslt = ','.join((','.join((''.join(tlp)for tlp in itrs.combinations(s,r)))
                                       for r in range(1,len(s)+1)))
print(rslt)

'a,b,c,ab,ac,bc,abc'

---

简洁些~

from itertools import chain, combinations as combs
chn_itr = chain.from_iterable
s = "abc"
print([''.join(x)for x in chn_itr(combs(s,r)for r in range(1,len(s)+1))])

['a', 'b', 'c', 'ab', 'ac', 'bc', 'abc']

Answer 2

考虑算法实现吧，穷举的js

var str = "abc";
console.log(getStr(str))

function getStr(str) {
  var len = str.length;
  var i, j;
  var res = [];
  for (i = 0; i <= len; i++) {
    for (j = i + 1; j <= len; j++) {
      res.push(str.substr(i, j))
    }
  }
  return res;
}