31 lines
1.2 KiB
JavaScript
Executable file
31 lines
1.2 KiB
JavaScript
Executable file
'use strict';
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var $ = require('../internals/export');
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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 toIntegerOrInfinity = require('../internals/to-integer-or-infinity');
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var toString = require('../internals/to-string');
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var stringSlice = uncurryThis(''.slice);
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var max = Math.max;
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var min = Math.min;
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// eslint-disable-next-line unicorn/prefer-string-slice -- required for testing
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var FORCED = !''.substr || 'ab'.substr(-1) !== 'b';
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// `String.prototype.substr` method
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// https://tc39.es/ecma262/#sec-string.prototype.substr
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$({ target: 'String', proto: true, forced: FORCED }, {
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substr: function substr(start, length) {
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var that = toString(requireObjectCoercible(this));
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var size = that.length;
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var intStart = toIntegerOrInfinity(start);
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var intLength, intEnd;
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if (intStart === Infinity) intStart = 0;
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if (intStart < 0) intStart = max(size + intStart, 0);
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intLength = length === undefined ? size : toIntegerOrInfinity(length);
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if (intLength <= 0 || intLength === Infinity) return '';
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intEnd = min(intStart + intLength, size);
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return intStart >= intEnd ? '' : stringSlice(that, intStart, intEnd);
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}
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});
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