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node_modules/es5-ext/string/#/at.js

@@ -0,0 +1,35 @@
+// Based on: https://github.com/mathiasbynens/String.prototype.at
+// Thanks @mathiasbynens !
+
+"use strict";
+
+var toInteger  = require("../../number/to-integer")
+  , validValue = require("../../object/valid-value");
+
+module.exports = function (pos) {
+	var str = String(validValue(this)), size = str.length, cuFirst, cuSecond, nextPos, len;
+	pos = toInteger(pos);
+
+	// Account for out-of-bounds indices
+	// The odd lower bound is because the ToInteger operation is
+	// going to round `n` to `0` for `-1 < n <= 0`.
+	if (pos <= -1 || pos >= size) return "";
+
+	// Second half of `ToInteger`
+	// eslint-disable-next-line no-bitwise
+	pos |= 0;
+	// Get the first code unit and code unit value
+	cuFirst = str.charCodeAt(pos);
+	nextPos = pos + 1;
+	len = 1;
+	if (
+		// Check if it’s the start of a surrogate pair
+		cuFirst >= 0xd800 &&
+		cuFirst <= 0xdbff && // High surrogate
+		size > nextPos // There is a next code unit
+	) {
+		cuSecond = str.charCodeAt(nextPos);
+		if (cuSecond >= 0xdc00 && cuSecond <= 0xdfff) len = 2; // Low surrogate
+	}
+	return str.slice(pos, pos + len);
+};