包括左版本和右版本的预分配。 对于小块，这和RegExp impl一样快，但是随着块大小的增加，速度会更快。它的内存效率很高。

function chunkLeft (str, size = 3) {
  if (typeof str === 'string') {
    const length = str.length
    const chunks = Array(Math.ceil(length / size))
    for (let i = 0, index = 0; index < length; i++) {
      chunks[i] = str.slice(index, index += size)
    }
    return chunks
  }
}

function chunkRight (str, size = 3) {
  if (typeof str === 'string') {
    const length = str.length
    const chunks = Array(Math.ceil(length / size))
    if (length) {
      chunks[0] = str.slice(0, length % size || size)
      for (let i = 1, index = chunks[0].length; index < length; i++) {
        chunks[i] = str.slice(index, index += size)
      }
    }
    return chunks
  }
}

console.log(chunkRight())  // undefined
console.log(chunkRight(''))  // []
console.log(chunkRight('1'))  // ["1"]
console.log(chunkRight('123'))  // ["123"]
console.log(chunkRight('1234'))  // ["1", "234"]
console.log(chunkRight('12345'))  // ["12", "345"]
console.log(chunkRight('123456'))  // ["123", "456"]
console.log(chunkRight('1234567'))  // ["1", "234", "567"]

const getChunksFromString = (str, chunkSize) => {
    var regexChunk = new RegExp(`.{1,${chunkSize}}`, 'g')   // '.' represents any character
    return str.match(regexChunk)
}

根据需要调用它

console.log(getChunksFromString("Hello world", 3))   // ["Hel", "lo ", "wor", "ld"]

惊喜!你可以使用split来分割。

var parts = "1234567890 ".split(/(.{2})/).filter(O=>O)

结果显示['12'，'34'，'56'，'78'，'90'，' ']

使用slice()方法:

function returnChunksArray(str, chunkSize) {
  var arr = [];
  while(str !== '') {
    arr.push(str.slice(0, chunkSize));
    str = str.slice(chunkSize);
  }
  return arr;
}

使用substring()方法也可以做到这一点。

function returnChunksArray(str, chunkSize) {
  var arr = [];
  while(str !== '') {
    arr.push(str.substring(0, chunkSize));
    str = str.substring(chunkSize);
  }
  return arr;
}

    window.format = function(b, a) {
        if (!b || isNaN(+a)) return a;
        var a = b.charAt(0) == "-" ? -a : +a,
            j = a < 0 ? a = -a : 0,
            e = b.match(/[^\d\-\+#]/g),
            h = e && e[e.length - 1] || ".",
            e = e && e[1] && e[0] || ",",
            b = b.split(h),
            a = a.toFixed(b[1] && b[1].length),
            a = +a + "",
            d = b[1] && b[1].lastIndexOf("0"),
            c = a.split(".");
        if (!c[1] || c[1] && c[1].length <= d) a = (+a).toFixed(d + 1);
        d = b[0].split(e);
        b[0] = d.join("");
        var f = b[0] && b[0].indexOf("0");
        if (f > -1)
            for (; c[0].length < b[0].length - f;) c[0] = "0" + c[0];
        else +c[0] == 0 && (c[0] = "");
        a = a.split(".");
        a[0] = c[0];
        if (c = d[1] && d[d.length -
                1].length) {
            for (var d = a[0], f = "", k = d.length % c, g = 0, i = d.length; g < i; g++) f += d.charAt(g), !((g - k + 1) % c) && g < i - c && (f += e);
            a[0] = f
        }
        a[1] = b[1] && a[1] ? h + a[1] : "";
        return (j ? "-" : "") + a[0] + a[1]
    };

var str="1234567890";
var formatstr=format( "##,###.", str);
alert(formatstr);


This will split the string in reverse order with comma separated after 3 char's. If you want you can change the position.

function chunkString(str, length = 10) {
    let result = [],
        offset = 0;
    if (str.length <= length) return result.push(str) && result;
    while (offset < str.length) {
        result.push(str.substr(offset, length));
        offset += length;
    }
    return result;
}