4D Doc Center : WA Evaluate JavaScript

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4D v14.3

WA Evaluate JavaScript


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.

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 date	Longint	4
Is integer	Longint	8
Is integer 64 bits	Longint	25
Is JSON null	Longint	255
Is LongInt	Longint	9
Is object	Longint	38
Is real	Longint	1
Is string var	Longint	24
Is text	Longint	2
Is time	Longint	11
Object array	Longint	39

Important: Handling complex type results (objects, dates, etc.) is only possible if the Web area uses the integrated Web Kit as the rendering engine.

Example 1

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

$result:=WA Execute 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 string var)

  //$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