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- 'use strict';
- var $ = require('../internals/export');
- var requireObjectCoercible = require('../internals/require-object-coercible');
- var toInteger = require('../internals/to-integer');
-
- var slice = ''.slice;
- var max = Math.max;
- var min = Math.min;
-
- // `String.prototype.substr` method
- // https://tc39.es/ecma262/#sec-string.prototype.substr
- $({ target: 'String', proto: true }, {
- substr: function substr(start, length) {
- var that = String(requireObjectCoercible(this));
- var size = that.length;
- var intStart = toInteger(start);
- var intLength, intEnd;
- if (intStart === Infinity) intStart = 0;
- if (intStart < 0) intStart = max(size + intStart, 0);
- intLength = length === undefined ? size : toInteger(length);
- if (intLength <= 0 || intLength === Infinity) return '';
- intEnd = min(intStart + intLength, size);
- return intStart >= intEnd ? '' : slice.call(that, intStart, intEnd);
- }
- });
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