17 lines
613 B
JavaScript
17 lines
613 B
JavaScript
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var toInteger = require('./$.to-integer')
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, defined = require('./$.defined');
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// true -> String#at
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// false -> String#codePointAt
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module.exports = function(TO_STRING){
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return function(that, pos){
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var s = String(defined(that))
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, i = toInteger(pos)
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, l = s.length
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, a, b;
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if(i < 0 || i >= l)return TO_STRING ? '' : undefined;
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a = s.charCodeAt(i);
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return a < 0xd800 || a > 0xdbff || i + 1 === l || (b = s.charCodeAt(i + 1)) < 0xdc00 || b > 0xdfff
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? TO_STRING ? s.charAt(i) : a
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: TO_STRING ? s.slice(i, i + 2) : (a - 0xd800 << 10) + (b - 0xdc00) + 0x10000;
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};
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};
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