前段时间，一直在捣鼓着这么把数字形式的金额转换为项目中所需的格式，使用过单纯的js方法，最后在老大的指点下，才发现了另外一种很好用的方法：使用accounting.js。

accounting.js 是一个非常小的JavaScript方法库用于对数字，金额和货币进行格式化，并提供可选的Excel风格列渲染。它没有依赖任何JS框架。货币符号等可以按需求进行定制。它的代码如下：

1 /*!  2  * accounting.js v0.3.2  3  * Copyright 2011, Joss Crowcroft  4  *  5  * Freely distributable under the MIT license.  6  * Portions of accounting.js are inspired or borrowed from underscore.js  7  *  8  * Full details and documentation:  9  * http://josscrowcroft.github.com/accounting.js/ 10  */ 11  12 (function(root, undefined) { 13  14     /* --- Setup --- */ 15  16     // Create the local library object, to be exported or referenced globally later 17     var lib = {}; 18  19     // Current version 20     lib.version = '0.3.2'; 21  22  23     /* --- Exposed settings --- */ 24  25     // The library's settings configuration object. Contains default parameters for 26     // currency and number formatting 27     lib.settings = { 28         currency: { 29             symbol : "$",        // default currency symbol is '$' 30             format : "%s%v",    // controls output: %s = symbol, %v = value (can be object, see docs) 31             decimal : ".",        // decimal point separator 32             thousand : ",",        // thousands separator 33             precision : 2,        // decimal places 34             grouping : 3        // digit grouping (not implemented yet) 35         }, 36         number: { 37             precision : 0,        // default precision on numbers is 0 38             grouping : 3,        // digit grouping (not implemented yet) 39             thousand : ",", 40             decimal : "." 41         } 42     }; 43  44  45     /* --- Internal Helper Methods --- */ 46  47     // Store reference to possibly-available ECMAScript 5 methods for later 48     var nativeMap = Array.prototype.map, 49         nativeIsArray = Array.isArray, 50         toString = Object.prototype.toString; 51  52     /** 53      * Tests whether supplied parameter is a string 54      * from underscore.js 55      */ 56     function isString(obj) { 57         return !!(obj === '' || (obj && obj.charCodeAt && obj.substr)); 58     } 59  60     /** 61      * Tests whether supplied parameter is a string 62      * from underscore.js, delegates to ECMA5's native Array.isArray 63      */ 64     function isArray(obj) { 65         return nativeIsArray ? nativeIsArray(obj) : toString.call(obj) === '[object Array]'; 66     } 67  68     /** 69      * Tests whether supplied parameter is a true object 70      */ 71     function isObject(obj) { 72         return obj && toString.call(obj) === '[object Object]'; 73     } 74  75     /** 76      * Extends an object with a defaults object, similar to underscore's _.defaults 77      * 78      * Used for abstracting parameter handling from API methods 79      */ 80     function defaults(object, defs) { 81         var key; 82         object = object || {}; 83         defs = defs || {}; 84         // Iterate over object non-prototype properties: 85         for (key in defs) { 86             if (defs.hasOwnProperty(key)) { 87                 // Replace values with defaults only if undefined (allow empty/zero values): 88                 if (object[key] == null) object[key] = defs[key]; 89             } 90         } 91         return object; 92     } 93  94     /** 95      * Implementation of `Array.map()` for iteration loops 96      * 97      * Returns a new Array as a result of calling `iterator` on each array value. 98      * Defers to native Array.map if available 99      */100     function map(obj, iterator, context) {101         var results = [], i, j;102 103         if (!obj) return results;104 105         // Use native .map method if it exists:106         if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);107 108         // Fallback for native .map:109         for (i = 0, j = obj.length; i < j; i++ ) {110             results[i] = iterator.call(context, obj[i], i, obj);111         }112         return results;113     }114 115     /**116      * Check and normalise the value of precision (must be positive integer)117      */118     function checkPrecision(val, base) {119         val = Math.round(Math.abs(val));120         return isNaN(val)? base : val;121     }122 123 124     /**125      * Parses a format string or object and returns format obj for use in rendering126      *127      * `format` is either a string with the default (positive) format, or object128      * containing `pos` (required), `neg` and `zero` values (or a function returning129      * either a string or object)130      *131      * Either string or format.pos must contain "%v" (value) to be valid132      */133     function checkCurrencyFormat(format) {134         var defaults = lib.settings.currency.format;135 136         // Allow function as format parameter (should return string or object):137         if ( typeof format === "function" ) format = format();138 139         // Format can be a string, in which case `value` ("%v") must be present:140         if ( isString( format ) && format.match("%v") ) {141 142             // Create and return positive, negative and zero formats:143             return {144                 pos : format,145                 neg : format.replace("-", "").replace("%v", "-%v"),146                 zero : format147             };148 149         // If no format, or object is missing valid positive value, use defaults:150         } else if ( !format || !format.pos || !format.pos.match("%v") ) {151 152             // If defaults is a string, casts it to an object for faster checking next time:153             return ( !isString( defaults ) ) ? defaults : lib.settings.currency.format = {154                 pos : defaults,155                 neg : defaults.replace("%v", "-%v"),156                 zero : defaults157             };158 159         }160         // Otherwise, assume format was fine:161         return format;162     }163 164 165     /* --- API Methods --- */166 167     /**168      * Takes a string/array of strings, removes all formatting/cruft and returns the raw float value169      * alias: accounting.`parse(string)`170      *171      * Decimal must be included in the regular expression to match floats (defaults to172      * accounting.settings.number.decimal), so if the number uses a non-standard decimal 173      * separator, provide it as the second argument.174      *175      * Also matches bracketed negatives (eg. "$ (1.99)" => -1.99)176      *177      * Doesn't throw any errors (`NaN`s become 0) but this may change in future178      */179     var unformat = lib.unformat = lib.parse = function(value, decimal) {180         // Recursively unformat arrays:181         if (isArray(value)) {182             return map(value, function(val) {183                 return unformat(val, decimal);184             });185         }186 187         // Fails silently (need decent errors):188         value = value || 0;189 190         // Return the value as-is if it's already a number:191         if (typeof value === "number") return value;192 193         // Default decimal point comes from settings, but could be set to eg. "," in opts:194         decimal = decimal || lib.settings.number.decimal;195 196          // Build regex to strip out everything except digits, decimal point and minus sign:197         var regex = new RegExp("[^0-9-" + decimal + "]", ["g"]),198             unformatted = parseFloat(199                 ("" + value)200                 .replace(/\((.*)\)/, "-$1") // replace bracketed values with negatives201                 .replace(regex, '')         // strip out any cruft202                 .replace(decimal, '.')      // make sure decimal point is standard203             );204 205         // This will fail silently which may cause trouble, let's wait and see:206         return !isNaN(unformatted) ? unformatted : 0;207     };208 209 210     /**211      * Implementation of toFixed() that treats floats more like decimals212      *213      * Fixes binary rounding issues (eg. (0.615).toFixed(2) === "0.61") that present214      * problems for accounting- and finance-related software.215      */216     var toFixed = lib.toFixed = function(value, precision) {217         precision = checkPrecision(precision, lib.settings.number.precision);218         var power = Math.pow(10, precision);219 220         // Multiply up by precision, round accurately, then divide and use native toFixed():221         return (Math.round(lib.unformat(value) * power) / power).toFixed(precision);222     };223 224 225     /**226      * Format a number, with comma-separated thousands and custom precision/decimal places227      *228      * Localise by overriding the precision and thousand / decimal separators229      * 2nd parameter `precision` can be an object matching `settings.number`230      */231     var formatNumber = lib.formatNumber = function(number, precision, thousand, decimal) {232         // Resursively format arrays:233         if (isArray(number)) {234             return map(number, function(val) {235                 return formatNumber(val, precision, thousand, decimal);236             });237         }238 239         // Clean up number:240         number = unformat(number);241 242         // Build options object from second param (if object) or all params, extending defaults:243         var opts = defaults(244                 (isObject(precision) ? precision : {245                     precision : precision,246                     thousand : thousand,247                     decimal : decimal248                 }),249                 lib.settings.number250             ),251 252             // Clean up precision253             usePrecision = checkPrecision(opts.precision),254 255             // Do some calc:256             negative = number < 0 ? "-" : "",257             base = parseInt(toFixed(Math.abs(number || 0), usePrecision), 10) + "",258             mod = base.length > 3 ? base.length % 3 : 0;259 260         // Format the number:261         return negative + (mod ? base.substr(0, mod) + opts.thousand : "") + base.substr(mod).replace(/(\d{3})(?=\d)/g, "$1" + opts.thousand) + (usePrecision ? opts.decimal + toFixed(Math.abs(number), usePrecision).split('.')[1] : "");262     };263 264 265     /**266      * Format a number into currency267      *268      * Usage: accounting.formatMoney(number, symbol, precision, thousandsSep, decimalSep, format)269      * defaults: (0, "$", 2, ",", ".", "%s%v")270      *271      * Localise by overriding the symbol, precision, thousand / decimal separators and format272      * Second param can be an object matching `settings.currency` which is the easiest way.273      *274      * To do: tidy up the parameters275      */276     var formatMoney = lib.formatMoney = function(number, symbol, precision, thousand, decimal, format) {277         // Resursively format arrays:278         if (isArray(number)) {279             return map(number, function(val){280                 return formatMoney(val, symbol, precision, thousand, decimal, format);281             });282         }283 284         // Clean up number:285         number = unformat(number);286 287         // Build options object from second param (if object) or all params, extending defaults:288         var opts = defaults(289                 (isObject(symbol) ? symbol : {290                     symbol : symbol,291                     precision : precision,292                     thousand : thousand,293                     decimal : decimal,294                     format : format295                 }),296                 lib.settings.currency297             ),298 299             // Check format (returns object with pos, neg and zero):300             formats = checkCurrencyFormat(opts.format),301 302             // Choose which format to use for this value:303             useFormat = number > 0 ? formats.pos : number < 0 ? formats.neg : formats.zero;304 305         // Return with currency symbol added:306         return useFormat.replace('%s', opts.symbol).replace('%v', formatNumber(Math.abs(number), checkPrecision(opts.precision), opts.thousand, opts.decimal));307     };308 309 310     /**311      * Format a list of numbers into an accounting column, padding with whitespace312      * to line up currency symbols, thousand separators and decimals places313      *314      * List should be an array of numbers315      * Second parameter can be an object containing keys that match the params316      *317      * Returns array of accouting-formatted number strings of same length318      *319      * NB: `white-space:pre` CSS rule is required on the list container to prevent320      * browsers from collapsing the whitespace in the output strings.321      */322     lib.formatColumn = function(list, symbol, precision, thousand, decimal, format) {323         if (!list) return [];324 325         // Build options object from second param (if object) or all params, extending defaults:326         var opts = defaults(327                 (isObject(symbol) ? symbol : {328                     symbol : symbol,329                     precision : precision,330                     thousand : thousand,331                     decimal : decimal,332                     format : format333                 }),334                 lib.settings.currency335             ),336 337             // Check format (returns object with pos, neg and zero), only need pos for now:338             formats = checkCurrencyFormat(opts.format),339 340             // Whether to pad at start of string or after currency symbol:341             padAfterSymbol = formats.pos.indexOf("%s") < formats.pos.indexOf("%v") ? true : false,342 343             // Store value for the length of the longest string in the column:344             maxLength = 0,345 346             // Format the list according to options, store the length of the longest string:347             formatted = map(list, function(val, i) {348                 if (isArray(val)) {349                     // Recursively format columns if list is a multi-dimensional array:350                     return lib.formatColumn(val, opts);351                 } else {352                     // Clean up the value353                     val = unformat(val);354 355                     // Choose which format to use for this value (pos, neg or zero):356                     var useFormat = val > 0 ? formats.pos : val < 0 ? formats.neg : formats.zero,357 358                         // Format this value, push into formatted list and save the length:359                         fVal = useFormat.replace('%s', opts.symbol).replace('%v', formatNumber(Math.abs(val), checkPrecision(opts.precision), opts.thousand, opts.decimal));360 361                     if (fVal.length > maxLength) maxLength = fVal.length;362                     return fVal;363                 }364             });365 366         // Pad each number in the list and send back the column of numbers:367         return map(formatted, function(val, i) {368             // Only if this is a string (not a nested array, which would have already been padded):369             if (isString(val) && val.length < maxLength) {370                 // Depending on symbol position, pad after symbol or at index 0:371                 return padAfterSymbol ? val.replace(opts.symbol, opts.symbol+(new Array(maxLength - val.length + 1).join(" "))) : (new Array(maxLength - val.length + 1).join(" ")) + val;372             }373             return val;374         });375     };376 377 378     /* --- Module Definition --- */379 380     // Export accounting for CommonJS. If being loaded as an AMD module, define it as such.381     // Otherwise, just add `accounting` to the global object382     if (typeof exports !== 'undefined') {383         if (typeof module !== 'undefined' && module.exports) {384             exports = module.exports = lib;385         }386         exports.accounting = lib;387     } else if (typeof define === 'function' && define.amd) {388         // Return the library as an AMD module:389         define([], function() {390             return lib;391         });392     } else {393         // Use accounting.noConflict to restore `accounting` back to its original value.394         // Returns a reference to the library's `accounting` object;395         // e.g. `var numbers = accounting.noConflict();`396         lib.noConflict = (function(oldAccounting) {397             return function() {398                 // Reset the value of the root's `accounting` variable:399                 root.accounting = oldAccounting;400                 // Delete the noConflict method:401                 lib.noConflict = undefined;402                 // Return reference to the library to re-assign it:403                 return lib;404             };405         })(root.accounting);406 407         // Declare `fx` on the root (global/window) object:408         root['accounting'] = lib;409     }410 411     // Root will be `window` in browser or `global` on the server:412 }(this));

  而它的使用则更加方便，只是在项目中引入accounting.js，就可以直接使用了，比如：

1.formatMoney

// Default usage:accounting.formatMoney(99999999); //$99,999,999.00// European formatting (custom symbol and separators), could also use options object as second param:accounting.formatMoney(4999.99, "€", 2, ".", ","); // €4.999,99// Negative values are formatted nicely, too:accounting.formatMoney(-800000, "£ ", 0); // £ -800,000// Simple `format` string allows control of symbol position [%v = value, %s = symbol]:accounting.formatMoney(999999999, { symbol: "GBP",  format: "%v %s" }); // 999,999,999.00 GBP

 

2.formatNumber

accounting.formatNumber(999999999); // 999,999,999accounting.formatNumber(9876543.21, 3, " "); // 9 876 543.210

 

3.unformat

accounting.unformat("£ 12,345,678.90 GBP"); // 12345678.9

 

 

经过自己的实践，觉得这种方法是“金额转换”中最简便的方法，也希望自己以后可以记住，同样可以帮助到其他小伙伴们。