2 var $ = require('../internals/export');
3 var uncurryThis = require('../internals/function-uncurry-this');
4 var requireObjectCoercible = require('../internals/require-object-coercible');
5 var toIntegerOrInfinity = require('../internals/to-integer-or-infinity');
6 var toString = require('../internals/to-string');
8 var stringSlice = uncurryThis(''.slice);
12 // eslint-disable-next-line unicorn/prefer-string-slice -- required for testing
13 var FORCED = !''.substr || 'ab'.substr(-1) !== 'b';
15 // `String.prototype.substr` method
16 // https://tc39.es/ecma262/#sec-string.prototype.substr
17 $({ target: 'String', proto: true, forced: FORCED }, {
18 substr: function substr(start, length) {
19 var that = toString(requireObjectCoercible(this));
20 var size = that.length;
21 var intStart = toIntegerOrInfinity(start);
22 var intLength, intEnd;
23 if (intStart === Infinity) intStart = 0;
24 if (intStart < 0) intStart = max(size + intStart, 0);
25 intLength = length === undefined ? size : toIntegerOrInfinity(length);
26 if (intLength <= 0 || intLength === Infinity) return '';
27 intEnd = min(intStart + intLength, size);
28 return intStart >= intEnd ? '' : stringSlice(that, intStart, intEnd);