以原型函数的形式:

String.prototype.lsplit = function(){
    return this.match(new RegExp('.{1,'+ ((arguments.length==1)?(isFinite(String(arguments[0]).trim())?arguments[0]:false):1) +'}', 'g'));
}

这是我使用的代码，它使用string。prototype。slice。

是的，这是一个相当长的答案，因为它试图遵循当前的标准尽可能接近，当然包含了合理数量的JSDOC评论。然而，一旦缩小，代码只有828字节，一旦gzip传输，它只有497字节。

这个添加到String中的1方法。prototype(使用Object.defineProperty如果可用)是:

toChunks

包含了许多测试来检查功能。

担心代码的长度会影响性能?不用担心，http://jsperf.com/chunk-string/3

许多额外的代码是为了确保代码在多个javascript环境中响应相同。

/*jslint maxlen:80, browser:true, devel:true */ /* * Properties used by toChunks. */ /*property MAX_SAFE_INTEGER, abs, ceil, configurable, defineProperty, enumerable, floor, length, max, min, pow, prototype, slice, toChunks, value, writable */ /* * Properties used in the testing of toChunks implimentation. */ /*property appendChild, createTextNode, floor, fromCharCode, getElementById, length, log, pow, push, random, toChunks */ (function () { 'use strict'; var MAX_SAFE_INTEGER = Number.MAX_SAFE_INTEGER || Math.pow(2, 53) - 1; /** * Defines a new property directly on an object, or modifies an existing * property on an object, and returns the object. * * @private * @function * @param {Object} object * @param {string} property * @param {Object} descriptor * @return {Object} * @see https://goo.gl/CZnEqg */ function $defineProperty(object, property, descriptor) { if (Object.defineProperty) { Object.defineProperty(object, property, descriptor); } else { object[property] = descriptor.value; } return object; } /** * Returns true if the operands are strictly equal with no type conversion. * * @private * @function * @param {*} a * @param {*} b * @return {boolean} * @see http://www.ecma-international.org/ecma-262/5.1/#sec-11.9.4 */ function $strictEqual(a, b) { return a === b; } /** * Returns true if the operand inputArg is undefined. * * @private * @function * @param {*} inputArg * @return {boolean} */ function $isUndefined(inputArg) { return $strictEqual(typeof inputArg, 'undefined'); } /** * The abstract operation throws an error if its argument is a value that * cannot be converted to an Object, otherwise returns the argument. * * @private * @function * @param {*} inputArg The object to be tested. * @throws {TypeError} If inputArg is null or undefined. * @return {*} The inputArg if coercible. * @see https://goo.gl/5GcmVq */ function $requireObjectCoercible(inputArg) { var errStr; if (inputArg === null || $isUndefined(inputArg)) { errStr = 'Cannot convert argument to object: ' + inputArg; throw new TypeError(errStr); } return inputArg; } /** * The abstract operation converts its argument to a value of type string * * @private * @function * @param {*} inputArg * @return {string} * @see https://people.mozilla.org/~jorendorff/es6-draft.html#sec-tostring */ function $toString(inputArg) { var type, val; if (inputArg === null) { val = 'null'; } else { type = typeof inputArg; if (type === 'string') { val = inputArg; } else if (type === 'undefined') { val = type; } else { if (type === 'symbol') { throw new TypeError('Cannot convert symbol to string'); } val = String(inputArg); } } return val; } /** * Returns a string only if the arguments is coercible otherwise throws an * error. * * @private * @function * @param {*} inputArg * @throws {TypeError} If inputArg is null or undefined. * @return {string} */ function $onlyCoercibleToString(inputArg) { return $toString($requireObjectCoercible(inputArg)); } /** * The function evaluates the passed value and converts it to an integer. * * @private * @function * @param {*} inputArg The object to be converted to an integer. * @return {number} If the target value is NaN, null or undefined, 0 is * returned. If the target value is false, 0 is returned * and if true, 1 is returned. * @see http://www.ecma-international.org/ecma-262/5.1/#sec-9.4 */ function $toInteger(inputArg) { var number = +inputArg, val = 0; if ($strictEqual(number, number)) { if (!number || number === Infinity || number === -Infinity) { val = number; } else { val = (number > 0 || -1) * Math.floor(Math.abs(number)); } } return val; } /** * The abstract operation ToLength converts its argument to an integer * suitable for use as the length of an array-like object. * * @private * @function * @param {*} inputArg The object to be converted to a length. * @return {number} If len <= +0 then +0 else if len is +INFINITY then * 2^53-1 else min(len, 2^53-1). * @see https://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength */ function $toLength(inputArg) { return Math.min(Math.max($toInteger(inputArg), 0), MAX_SAFE_INTEGER); } if (!String.prototype.toChunks) { /** * This method chunks a string into an array of strings of a specified * chunk size. * * @function * @this {string} The string to be chunked. * @param {Number} chunkSize The size of the chunks that the string will * be chunked into. * @returns {Array} Returns an array of the chunked string. */ $defineProperty(String.prototype, 'toChunks', { enumerable: false, configurable: true, writable: true, value: function (chunkSize) { var str = $onlyCoercibleToString(this), chunkLength = $toInteger(chunkSize), chunked = [], numChunks, length, index, start, end; if (chunkLength < 1) { return chunked; } length = $toLength(str.length); numChunks = Math.ceil(length / chunkLength); index = 0; start = 0; end = chunkLength; chunked.length = numChunks; while (index < numChunks) { chunked[index] = str.slice(start, end); start = end; end += chunkLength; index += 1; } return chunked; } }); } }()); /* * Some tests */ (function () { 'use strict'; var pre = document.getElementById('out'), chunkSizes = [], maxChunkSize = 512, testString = '', maxTestString = 100000, chunkSize = 0, index = 1; while (chunkSize < maxChunkSize) { chunkSize = Math.pow(2, index); chunkSizes.push(chunkSize); index += 1; } index = 0; while (index < maxTestString) { testString += String.fromCharCode(Math.floor(Math.random() * 95) + 32); index += 1; } function log(result) { pre.appendChild(document.createTextNode(result + '\n')); } function test() { var strLength = testString.length, czLength = chunkSizes.length, czIndex = 0, czValue, result, numChunks, pass; while (czIndex < czLength) { czValue = chunkSizes[czIndex]; numChunks = Math.ceil(strLength / czValue); result = testString.toChunks(czValue); czIndex += 1; log('chunksize: ' + czValue); log(' Number of chunks:'); log(' Calculated: ' + numChunks); log(' Actual:' + result.length); pass = result.length === numChunks; log(' First chunk size: ' + result[0].length); pass = pass && result[0].length === czValue; log(' Passed: ' + pass); log(''); } } test(); log(''); log('Simple test result'); log('abcdefghijklmnopqrstuvwxyz'.toChunks(3)); }()); <pre id="out"></pre>

那么下面这一小段代码呢:

function splitME(str, size) {
    let subStr = new RegExp('.{1,' + size + '}', 'g');
    return str.match(subStr);
};

    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.

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"]

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"]