Is valid GlideRecord (#895)

* Create readme.md

* Create create_admin_user.js

* Create isValidGlideRecord.js

* Create is_valid_GlideRecord.js

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* Delete GlideRecord/isValidGlideRecord/is_valid_GlideRecord.js

* Create readme.md

Initial commit

Author: mskoddow

GlideRecord/isValidGlideRecord/isValidGlideRecord.js

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+/*
+ * Tests whether passed value in parameter `grRecordInstance` represents a valid GlideRecord instance.
+ * 
+ * @param {Object} grRecordInstance
+ *   Reference to an instance of a GlideRecord object.
+ * @param {Object} [strTableName]
+ *   If specified an additional check of the GlideRecord against the given table name is performed.
+ * @returns {Object}
+ *   Name of the table for which the GlideRecord was instantiated.
+ * @throws TypeError
+ *   In case value of parameter `strTableName` is not a string or parameter count is 0. 
+ */
+function isValidGlideRecord(grRecordInstance, strTableName) {
+	
+	if (arguments.length === 0) {
+		throw new TypeError('At least one parameter value is expected!');
+	}
+	
+	if (arguments.length > 1 && (typeof strTableName !== 'string' || strTableName.length === 0)) {
+		throw new TypeError('Value of parameter "strTableName" does not represent a valid string!');		
+	}
+	
+	var _strTableName = String(strTableName || '').trim();
+	
+	var _isValid = 
+		grRecordInstance &&
+		typeof grRecordInstance === 'object' &&
+		grRecordInstance instanceof GlideRecord &&
+		!grRecordInstance.isNewRecord() &&
+		grRecordInstance.isValidRecord();
+	
+	
+	if (_strTableName.length > 0) {
+		_isValid = _isValid && grRecordInstance.getTableName() === strTableName;
+	}
+
+	return _isValid;
+};

GlideRecord/isValidGlideRecord/readme.md

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+# Description
+
+Many developers are building functions which expect any GlideRecord reference as a function parameter but within these functions they do no check whether the passed value really represents a valid GlideRecord. However to test a function parameter for a valid GlideRecord reference is pretty tricky and extensive. Therefore I built a small helper function `isValidGlideRecord` which will do the job. As a second optional parameter you can specify a table name which will be considered for an additional validation.
+
+# Usage
+
+```
+var grIncident = new GlideRecord('incident');
+
+grIncident.get('12345678901234567890123456789012');
+
+gs.info(isValidGlideRecord(grIncident, 'incident'));
+```