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26 lines
818 B
26 lines
818 B
// Based on: https://github.com/mathiasbynens/String.prototype.codePointAt |
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// Thanks @mathiasbynens ! |
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"use strict"; |
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var toInteger = require("../../../number/to-integer") |
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, validValue = require("../../../object/valid-value"); |
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module.exports = function (pos) { |
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var str = String(validValue(this)), length = str.length, first, second; |
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pos = toInteger(pos); |
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// Account for out-of-bounds indices: |
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if (pos < 0 || pos >= length) return undefined; |
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// Get the first code unit |
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first = str.charCodeAt(pos); |
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if (first >= 0xd800 && first <= 0xdbff && length > pos + 1) { |
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second = str.charCodeAt(pos + 1); |
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if (second >= 0xdc00 && second <= 0xdfff) { |
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// http://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae |
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return (first - 0xd800) * 0x400 + second - 0xdc00 + 0x10000; |
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} |
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} |
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return first; |
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};
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