34 lines
597 B
JavaScript
34 lines
597 B
JavaScript
'use strict';
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var numberIsNan = require('number-is-nan');
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module.exports = function (str, pos) {
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if (str === null || str === undefined) {
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throw TypeError();
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}
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str = String(str);
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var size = str.length;
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var i = pos ? Number(pos) : 0;
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if (numberIsNan(i)) {
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i = 0;
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}
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if (i < 0 || i >= size) {
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return undefined;
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}
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var first = str.charCodeAt(i);
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if (first >= 0xD800 && first <= 0xDBFF && size > i + 1) {
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var second = str.charCodeAt(i + 1);
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if (second >= 0xDC00 && second <= 0xDFFF) {
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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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