传入数字,Number.prototype.format

Question

我已经看到在几个站点上引用了这个格式函数,但它们都没有一个如何将数字传入函数的明确示例.

我试过'12345'.format('0.00'),我相信它应该如何写,但它给了我一个错误,该对象不支持属性或方法.我也试过Number('12345').format('0.00'); var num ='12345'// num.format('0.00'); 格式('0.00','12345')甚至尝试使用数字而不是字符串12345.format(0.00).我错过了一些非常明显的东西吗？

包含的功能副本供参考,因此您无需访问该站点(填写所有缺失的部分).

/**
 * I ? Google
 */
String.prototype.stripNonNumeric = function() {
    var str = this + '';
    var rgx = /^\d|\.|-$/;
    var out = '';
    for( var i = 0; i < str.length; i++ ) {
        if( rgx.test( str.charAt(i) ) ) {
            if( !( ( str.charAt(i) == '.' && out.indexOf( '.' ) != -1 ) ||
            ( str.charAt(i) == '-' && out.length != 0 ) ) ) {
                out += str.charAt(i);
            }
        }
    }
    return out;
};

/**
 * Formats the number according to the 'format' string; adherses to the american number standard where a comma is inserted after every 3 digits.
 *  note: there should be only 1 contiguous number in the format, where a number consists of digits, period, and commas
 *        any other characters can be wrapped around this number, including '$', '%', or text
 *        examples (123456.789):
 *          '0' - (123456) show only digits, no precision
 *          '0.00' - (123456.78) show only digits, 2 precision
 *          '0.0000' - (123456.7890) show only digits, 4 precision
 *          '0,000' - (123,456) show comma and digits, no precision
 *          '0,000.00' - (123,456.78) show comma and digits, 2 precision
 *          '0,0.00' - (123,456.78) shortcut method, show comma and digits, 2 precision
 *
 * @method format
 * @param format {string} the way you would like to format this text
 * @return {string} the formatted number
 * @public
 */
Number.prototype.format = function(format) {
    if (!(typeof format == "string")) {return '';} // sanity check

    var hasComma = -1 < format.indexOf(','),
        psplit = format.stripNonNumeric().split('.'),
        that = this;

    // compute precision
    if (1 < psplit.length) {
        // fix number precision
        that = that.toFixed(psplit[1].length);
    }
    // error: too many periods
    else if (2 < psplit.length) {
        throw('NumberFormatException: invalid format, formats should have no more than 1 period: ' + format);
    }
    // remove precision
    else {
        that = that.toFixed(0);
    }

    // get the string now that precision is correct
    var fnum = that.toString();

    // format has comma, then compute commas
    if (hasComma) {
        // remove precision for computation
        psplit = fnum.split('.');

        var cnum = psplit[0],
            parr = [],
            j = cnum.length,
            m = Math.floor(j / 3),
            n = cnum.length % 3 || 3; // n cannot be ZERO or causes infinite loop

        // break the number into chunks of 3 digits; first chunk may be less than 3
        for (var i = 0; i < j; i += n) {
            if (i != 0) {n = 3;}
            parr[parr.length] = cnum.substr(i, n);
            m -= 1;
        }

        // put chunks back together, separated by comma
        fnum = parr.join(',');

        // add the precision back in
        if (psplit[1]) {fnum += '.' + psplit[1];}
    }

    // replace the number portion of the format with fnum
    return format.replace(/[\d,?\.?]+/, fnum);
};

Answer 1

这不是完整的代码 - 它缺少isType方法stripNonNumeric。但无论如何，由于它是 Number 对象本身的扩展，因此您可以将其用作：

(42).format('0.00');

或者

var a = 42;
a.format('0.00');

'12345'.format('0.00')不起作用，因为'12345'这里是一个字符串，但该方法仅针对数字定义。

请参阅这个问题，了解为什么您需要将数字括在括号内，以及如何在不使用括号的情况下绕过它，尽管我不会推荐它 - 因为所有这些关于维护程序员和轴之类的谣言。我并不是说每个维护程序员的背包里都带着一个，但为什么要冒险呢？他们也喜欢黑客，但不喜欢代码..哈哈哈哈