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Versão: v18

Área Web

Acesso a métodos 4D​

You can call 4D methods from the JavaScript code executed in a Web area and get values in return. To be able to call 4D methods from a Web area, you must activate the 4D methods accessibility property ("all").

This property is only available if the Web area uses the embedded Web rendering engine.

When this property is on, a special JavaScript object named $4d is instantiated in the Web area, which you can use to manage calls to 4D project methods.

Gramática JSON​

NomeTipo de dadosValores possíveis
methodsAccessibilitystring"none" (padrão), "all"

Objectos suportados​

Área Web

Progressão​

Nome de uma variável do tipo Longint. This variable will receive a value between 0 and 100, representing the page load completion percentage in the Web area. Atualizado automaticamente por 4D, não pode ser modificado manualmente.

Gramática JSON​

NomeTipo de dadosValores possíveis
progressSourcestringNome de uma variável Longint

Objectos suportados​

Área Web

URL​

A String type variable that designates the URL loaded or being loading by the associated Web area. The association between the variable and the Web area works in both directions:

  • If the user assigns a new URL to the variable, this URL is automatically loaded by the Web area.
  • Any browsing done within the Web area will automatically update the contents of the variable.

Schematically, this variable functions like the address area of a Web browser. Pode representá-lo através de uma área de texto por cima da área Web.

Variável URL e comando WA OPEN URL​

A variável URL produz os mesmos efeitos que o comando WA OPEN URL. No entanto, há que assinalar as seguintes diferenças:

  • For access to documents, this variable only accepts URLs that are RFC-compliant ("file://c:/My%20Doc") and not system pathnames ("c:\MyDoc"). O comando WA OPEN URL aceita ambas as notações.
  • If the URL variable contains an empty string, the Web area does not attempt to load the URL. The WA OPEN URL command generates an error in this case.
  • If the URL variable does not contain a protocol (http, mailto, file, etc.), the Web area adds "http://", which is not the case for the WA OPEN URL command.
  • When the Web area is not displayed in the form (when it is located on another page of the form), executing the WA OPEN URL command has no effect, whereas assigning a value to the URL variable can be used to update the current URL.

Gramática JSON​

NomeTipo de dadosValores possíveis
urlSourcestringUm URL.

Objectos suportados​

Área Web

Utilizar o motor de renderização Web integrado​

This option allows choosing between two rendering engines for the Web area, depending on the specifics of your application:

  • unchecked - JSON value: system (default): In this case, 4D uses the "best" engine corresponding to the system. On Windows, 4D automatically uses the most recent version of the browser found on the machine (IE11, MS Edge, etc.). No macOS, 4D usa a versão atual do WebKit (Safari). This means that you automatically benefit from the latest advances in Web rendering, through HTML5 or JavaScript. However, you may notice some rendering differences between Internet Explorer/Edge implementations and Web Kit ones.
  • checked - JSON value: embedded: In this case, 4D uses Blink engine from Google. Using the embedded Web engine means that Web area rendering and their functioning in your application are identical regardless of the platform used to run 4D (slight variations of pixels or differences related to network implementation may nevertheless be observed). When this option is chosen, you no longer benefit from automatic updates of the Web engine performed by the operating system; however, new versions of the engines are provided through 4D.

Observe que o motor Blink tem as seguintes restrições:

*   [WA SET PAGE CONTENT](https://doc.4d.com/4Dv18/4D/18.4/WA-SET-PAGE-CONTENT.301-5232965.en.html): using this command requires that at least one page is already loaded in the area (through a call to [WA OPEN URL](https://doc.4d.com/4Dv18/4D/18.4/WA-OPEN-URL.301-5232954.en.html) or an assignment to the URL variable associated to the area).
*   Execution of JavaScript is always enabled; execution of Java applets and plug-ins is always disabled. Esses parâmetros não podem ser alterados no Blink. The following selectors of the [WA SET PREFERENCE](https://doc.4d.com/4Dv18/4D/18.4/WA-SET-PREFERENCE.301-5232962.en.html) and [WA GET PREFERENCE](https://doc.4d.com/4Dv18/4D/18.4/WA-GET-PREFERENCE.301-5232945.en.html) commands are ignored:
    *   `WA enable Java applets`
    *   `WA enable JavaScript`
    *   `WA enable plugins`
*   When URL drops are enabled by the `WA enable URL drop` selector of the [WA SET PREFERENCE](https://doc.4d.com/4Dv18/4D/18.4/WA-SET-PREFERENCE.301-5232962.en.html) command, the first drop must be preceded by at least one call to [WA OPEN URL](https://doc.4d.com/4Dv18/4D/18.4/WA-OPEN-URL.301-5232954.en.html) or one assignment to the URL variable associated to the area.

Gramática JSON​

NomeTipo de dadosValores possíveis
webEnginestring"embedded", "system"

Objectos suportados​

Área Web