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2d441493a4
PR-URL: https://github.com/nodejs/io.js/pull/2286 Reviewed-By: Roman Reiss <me@silverwind.io>
27 lines
809 B
JavaScript
27 lines
809 B
JavaScript
// 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)), l = 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 >= l) 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) && (l > 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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