WA Evaluate JavaScript

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4D v17.4


WA Evaluate JavaScript ( {* ;} object ; jsCode {; type} ) -> Function result

Parameter	Type	Description
*	Operator	If specified, object is an object name (string) If omitted, object is a variable
object	Form object	Object name (if * is specified) or Variable (if * is omitted)
jsCode	String	JavaScript code
type	Longint	Type into which to convert result
Function result	Date, Object, Pointer, Real, Text, Time	Result of evaluation

Description

The WA Evaluate JavaScript command executes, in the Web area designated by the * and object parameters, the JavaScript code passed in jsCode and returns the result. This command must be called after the page is loaded (the On End URL Loading form event must have been generated).

By default, the command returns values as strings. You can use the optional type parameter to specify typing for the value returned. To do this, pass one of the following constants, found in the "Field and Variable Types" theme:

Constant	Type	Value
Is Boolean	Longint	6
Is collection	Longint	42
Is date	Longint	4
Is longint	Longint	9
Is object	Longint	38
Is real	Longint	1
Is text	Longint	2
Is time	Longint	11

Example 1

This example of JavaScript code causes the previous URL to be displayed:

$result:=WA Evaluate JavaScript(MyWArea;"history.back()")

Example 2

This example shows a few evaluations with conversion of the values received.

JavaScript functions placed in an HTML file:

<!DOCTYPE html>
<html>
    <head>
        <script>
        function evalLong(){
            return 123;
        }
        function evalText(){
            return "456";
        }
        function evalObject(){
            return {a:1,b:"hello world"};
        }
        function evalDate(){
            return new Date();
        }
    </script>
    </head>
    <body>
        TEST PAGE
    </body>
</html>

In the 4D form method, you write:

 If(Form event=On Load)

    WA OPEN URL(*;"Web Area";"C:\\myDatabase\\index.html")

 End if

You can then evaluate the JavaScript code from 4D:

 $Eval1:=WA Evaluate JavaScript(*;"Web Area";"evalLong()";Is longint)

  //$Eval1 = 123

  //$Eval1 = "123" if type is omitted

 $Eval2:=WA Evaluate JavaScript(*;"Web Area";"evalText()";Is text)

  //$Eval2 = "456"

 $Eval3:=WA Evaluate JavaScript(*;"Web Area";"evalObject()";Is object)

  //$Eval3 = {"a":1,"b":"hello world"}

 $Eval4:=WA Evaluate JavaScript(*;"Web Area";"evalDate()";Is date)

  // $Eval4 = 06/21/13

  // $Eval4 = "2013-06-21T14:45:09.694Z" if type is omitted