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30 lines
1.2 KiB
30 lines
1.2 KiB
'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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