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| // http://jsperf.com/padleft/2 | |
| /** | |
| * String.repeat('a', 5) = 'aaaaa' | |
| * String.repeat('ab', 5) = 'ababa' | |
| * String.repeat('abc', 5) = 'abcab' | |
| */ | |
| String.repeat = function repeat(str, len) { | |
| while (str.length < len) { | |
| if (str.length * 2 >= len) { | |
| return str + str.substring(0, len - str.length); | |
| } else { | |
| str += str; | |
| } | |
| } | |
| if (str.length == len) { | |
| return str; | |
| } | |
| return str.substring(0, len); | |
| }; | |
| /** | |
| * 'a'.padLeft('b', 5) = 'bbbba' | |
| * 'a'.padLeft('ab', 5) = 'ababa' | |
| * 'a'.padLeft('abc', 5) = 'abcaa' | |
| */ | |
| String.prototype.padLeft = function padLeft(pad, len) { | |
| if (this.length < len) { | |
| pad = pad || ' '; | |
| return String.repeat(pad, len - this.length) + this; | |
| } | |
| return this; | |
| }; | |
| /** | |
| * 'a'.padRight('b', 5) = 'abbbb' | |
| * 'a'.padRight('ab', 5) = 'aabab' | |
| * 'a'.padRight('abc', 5) = 'aabca' | |
| */ | |
| String.prototype.padRight = function padRight(pad, len) { | |
| if (this.length < len) { | |
| pad = pad || ' '; | |
| return '' + this + String.repeat(pad, len - this.length); | |
| } | |
| return this; | |
| }; |
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