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[Java教程]javascript sprintf方法


转载自: http://demon.tw/programming/javascript-sprintf.html

 1 function str_repeat(i, m) { 2   for (var o = []; m > 0; o[--m] = i); 3   return o.join(''); 4 } 5 function sprintf() { 6   var i = 0, a, f = arguments[i++], o = [], m, p, c, x, s = ''; 7   while (f) { 8     if (m = /^[^\x25]+/.exec(f)) { 9       o.push(m[0]);10     }11     else if (m = /^\x25{2}/.exec(f)) {12       o.push('%');13     }14     else if (m = /^\x25(?:(\d+)\$)?(\+)?(0|'[^$])?(-)?(\d+)?(?:\.(\d+))?([b-fosuxX])/.exec(f)) {15       if (((a = arguments[m[1] || i++]) == null) || (a == undefined)) {16         throw('Too few arguments.');17       }18       if (/[^s]/.test(m[7]) && (typeof(a) != 'number')) {19         throw('Expecting number but found ' + typeof(a));20       }21       switch (m[7]) {22         case 'b': a = a.toString(2); break;23         case 'c': a = String.fromCharCode(a); break;24         case 'd': a = parseInt(a); break;25         case 'e': a = m[6] ? a.toExponential(m[6]) : a.toExponential(); break;26         case 'f': a = m[6] ? parseFloat(a).toFixed(m[6]) : parseFloat(a); break;27         case 'o': a = a.toString(8); break;28         case 's': a = ((a = String(a)) && m[6] ? a.substring(0, m[6]) : a); break;29         case 'u': a = Math.abs(a); break;30         case 'x': a = a.toString(16); break;31         case 'X': a = a.toString(16).toUpperCase(); break;32       }33       a = (/[def]/.test(m[7]) && m[2] && a >= 0 ? '+'+ a : a);34       c = m[3] ? m[3] == '0' ? '0' : m[3].charAt(1) : ' ';35       x = m[5] - String(a).length - s.length;36       p = m[5] ? str_repeat(c, x) : '';37       o.push(s + (m[4] ? a + p : p + a));38     }39     else {40       throw('Huh ?!');41     }42     f = f.substring(m[0].length);43   }44   return o.join('');45 }