39 lines
1.2 KiB
JavaScript
39 lines
1.2 KiB
JavaScript
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// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/repeat
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if (!String.prototype.repeat) {
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String.prototype.repeat = function(count) {
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'use strict';
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if (this == null) {
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throw new TypeError('can\'t convert ' + this + ' to object');
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}
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var str = '' + this;
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count = +count;
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if (count != count) {
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count = 0;
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}
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if (count < 0) {
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throw new RangeError('repeat count must be non-negative');
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}
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if (count == Infinity) {
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throw new RangeError('repeat count must be less than infinity');
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}
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count = Math.floor(count);
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if (str.length == 0 || count == 0) {
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return '';
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}
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// Ensuring count is a 31-bit integer allows us to heavily optimize the
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// main part. But anyway, most current (August 2014) browsers can't handle
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// strings 1 << 28 chars or longer, so:
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if (str.length * count >= 1 << 28) {
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throw new RangeError('repeat count must not overflow maximum string size');
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}
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var maxCount = str.length * count;
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count = Math.floor(Math.log(count) / Math.log(2));
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while (count) {
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str += str;
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count--;
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}
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str += str.substring(0, maxCount - str.length);
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return str;
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}
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}
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