Is (function)

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IsArray(expression)

IsDate(expression)

IsEmpty(expression)

IsNull(expression)

IsNumeric(expression)

IsObject(expression)

Description

The Is functions return TRUE if a variable type corresponds to the function call, FALSE is returned otherwise. The required parameter, expression, is the variable whose type status is being determined.

IsDate() checks to see if the string is in a valid date format - it does not check to see if the date actually exists. IsDate("02/30/15") will return True. Additional checking will need to be done in your code to handle different date formats.

Example (Basic)

Rem Is Functions Example
Dim Children(3), Chef, When
TestVariable Children
Chef = 1
TestVariable Chef
When = Now
TestVariable When
Sub TestVariable(x)
  If IsArray(x) Then
    Print "The variable is an array."
  ElseIf IsDate(x) Then
    Print "The variable is a date."
  ElseIf IsNumeric(x) Then
    Print "The variable is a number."
  End If
End Sub

Example (JavaScript)

// Is Functions Example

var TestVariable=function(x) {
  if (!Array.isArray) {
    Array.isArray = function(x) {
      return Object.prototype.toString.call(x) === "[object Array]";
    };
  }

  IsDate = function(x) {
    return (null != x) && !isNaN(x) && ("undefined" !== typeof x.getDate);
  };

  IsNumeric = function(n) {
    return !isNaN(parseFloat(n)) && isFinite(n);
  };

  if (Array.isArray(x)) {
    document.write(("The variable is an array.") + "<br>");
  } else if (IsDate(x) ) {
    document.write(("The variable is a date.") + "<br>");
  } else if (IsNumeric(x) ) {
    document.write(("The variable is a number.") + "<br>");
  }
}

var Children=new Array(3), Chef, When;
TestVariable(Children);
var Chef = 1;
TestVariable(Chef);
var When = new Date();
TestVariable(When);

Output

The variable is an array.
The variable is a number.
The variable is a date.

Related Items

TypeName, VarType