41 lines
998 B
JavaScript
41 lines
998 B
JavaScript
function repeat(input, count) {
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if (input == null) {
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throw new TypeError("can't convert " + input + " to object");
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}
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let str = "" + input;
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// To convert string to integer.
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count = +count;
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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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const 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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module.exports = repeat;
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