44 lines
1.6 KiB
JavaScript
44 lines
1.6 KiB
JavaScript
'use strict';
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var $ = require('../internals/export');
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var call = require('../internals/function-call');
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var uncurryThis = require('../internals/function-uncurry-this');
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var requireObjectCoercible = require('../internals/require-object-coercible');
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var toString = require('../internals/to-string');
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var fails = require('../internals/fails');
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var $Array = Array;
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var charAt = uncurryThis(''.charAt);
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var charCodeAt = uncurryThis(''.charCodeAt);
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var join = uncurryThis([].join);
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// eslint-disable-next-line es/no-string-prototype-iswellformed-towellformed -- safe
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var $toWellFormed = ''.toWellFormed;
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var REPLACEMENT_CHARACTER = '\uFFFD';
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// Safari bug
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var TO_STRING_CONVERSION_BUG = $toWellFormed && fails(function () {
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return call($toWellFormed, 1) !== '1';
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});
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// `String.prototype.toWellFormed` method
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// https://github.com/tc39/proposal-is-usv-string
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$({ target: 'String', proto: true, forced: TO_STRING_CONVERSION_BUG }, {
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toWellFormed: function toWellFormed() {
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var S = toString(requireObjectCoercible(this));
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if (TO_STRING_CONVERSION_BUG) return call($toWellFormed, S);
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var length = S.length;
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var result = $Array(length);
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for (var i = 0; i < length; i++) {
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var charCode = charCodeAt(S, i);
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// single UTF-16 code unit
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if ((charCode & 0xF800) !== 0xD800) result[i] = charAt(S, i);
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// unpaired surrogate
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else if (charCode >= 0xDC00 || i + 1 >= length || (charCodeAt(S, i + 1) & 0xFC00) !== 0xDC00) result[i] = REPLACEMENT_CHARACTER;
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// surrogate pair
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else {
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result[i] = charAt(S, i);
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result[++i] = charAt(S, i);
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}
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} return join(result, '');
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}
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});
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