* Fetch example, demo how to reconstruct object response

packages/wasm-job/examples/fetch/loadstrings.lpi

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+<?xml version="1.0" encoding="UTF-8"?>
+<CONFIG>
+  <ProjectOptions>
+    <Version Value="12"/>
+    <General>
+      <Flags>
+        <MainUnitHasCreateFormStatements Value="False"/>
+        <MainUnitHasTitleStatement Value="False"/>
+        <MainUnitHasScaledStatement Value="False"/>
+        <UseDefaultCompilerOptions Value="True"/>
+      </Flags>
+      <SessionStorage Value="InProjectDir"/>
+      <Title Value="loadstrings"/>
+      <UseAppBundle Value="False"/>
+      <ResourceType Value="res"/>
+    </General>
+    <BuildModes>
+      <Item Name="Default" Default="True"/>
+    </BuildModes>
+    <PublishOptions>
+      <Version Value="2"/>
+      <UseFileFilters Value="True"/>
+    </PublishOptions>
+    <RunParams>
+      <FormatVersion Value="2"/>
+    </RunParams>
+    <Units>
+      <Unit>
+        <Filename Value="loadstrings.lpr"/>
+        <IsPartOfProject Value="True"/>
+        <UnitName Value="stringshelper"/>
+      </Unit>
+    </Units>
+  </ProjectOptions>
+  <CompilerOptions>
+    <Version Value="11"/>
+    <Target>
+      <Filename Value="loadstrings.wasm" ApplyConventions="False"/>
+    </Target>
+    <SearchPaths>
+      <IncludeFiles Value="$(ProjOutDir)"/>
+      <OtherUnitFiles Value="../../src"/>
+      <UnitOutputDirectory Value="lib/$(TargetCPU)-$(TargetOS)"/>
+    </SearchPaths>
+    <CodeGeneration>
+      <Subtarget Value="browser"/>
+    </CodeGeneration>
+    <Linking>
+      <Debugging>
+        <GenerateDebugInfo Value="False"/>
+      </Debugging>
+      <Options>
+        <ExecutableType Value="Library"/>
+      </Options>
+    </Linking>
+  </CompilerOptions>
+  <Debugging>
+    <Exceptions>
+      <Item>
+        <Name Value="EAbort"/>
+      </Item>
+      <Item>
+        <Name Value="ECodetoolError"/>
+      </Item>
+      <Item>
+        <Name Value="EFOpenError"/>
+      </Item>
+    </Exceptions>
+  </Debugging>
+</CONFIG>

packages/wasm-job/examples/fetch/loadstrings.lpr

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+library stringshelper;
+
+{$mode objfpc}
+{$h+}
+
+uses nothreads, classes, sysutils, variants, job.js;
+
+Type
+  // Define the necessary interfaces from the browser APIs.
+  IJSResponse = interface(IJSObject)
+    ['{0B705D5E-D166-325F-8AD5-004BD5C7161F}']
+    function text: IJSPromise; // Promise<USVString>
+  end;
+
+  IJSWindow = interface(IJSObject)
+    function fetch(const aInput: UnicodeString): IJSPromise; // Promise<Response>
+  end;
+
+  { TJSResponse }
+
+  TJSResponse = class(TJSObject,IJSResponse)
+  Protected
+    function text: IJSPromise; overload; // Promise<USVString>
+    class function Cast(aObj : IJSObject): IJSResponse;
+  end;
+
+  { TJSWindow }
+
+  TJSWindow = class(TJSObject,IJSWindow)
+    function fetch(const aInput: UnicodeString): IJSPromise; // Promise<Response>
+  end;
+
+  TLoadHelper = class(TObject)
+    FURL: string;
+    FStrings: TStrings;
+    constructor Create(aURL: string; AList: TStrings);
+    procedure LoadFromURL;
+    function LoadOK(const aRes: Variant): Variant;
+    function LoadJsonOK(const aRes: Variant): Variant;
+  end;
+
+  
+  TStringsHelper = class helper for TStrings
+     procedure LoadFromURL(const aURL: string);
+   end;
+
+  TApp = Class(TObject)
+  private
+    sl: TStringList;
+  public
+    procedure Run;
+  end;
+
+var
+  JSWindow : IJSWindow;
+
+{ TJSWindow }
+
+function TJSWindow.fetch(const aInput: UnicodeString): IJSPromise;
+
+begin
+  Result:=InvokeJSObjectResult('fetch',[aInput],TJSPromise) as IJSPromise;
+end;
+
+function TJSResponse.text: IJSPromise;
+
+begin
+  Result:=InvokeJSObjectResult('text',[],TJSPromise) as IJSPromise;
+end;
+
+class function TJSResponse.Cast(aObj: IJSObject): IJSResponse;
+begin
+  Result:=TJSResponse.JOBCast(aObj);
+end;
+
+
+{ TLoadHelper } 
+
+constructor TLoadHelper.Create(aURL: string; aList: TStrings);
+begin
+  FURL := aURL;
+  FStrings := AList;
+end;
+
+procedure TLoadHelper.LoadFromURL;
+begin
+  try
+    JSWindow.fetch(FURL)._then(@LoadOK);
+  except
+    Writeln('Aaaarrghhhh, error fetching :( :(');
+    Free; // Need to free ourselves
+  end;
+end;
+
+function TLoadHelper.LoadOK(const aRes: Variant): Variant;
+var
+  aUnknown : IUnknown;
+  aObject : IJSObject;
+  res: IJSResponse;
+begin
+  try
+    //fetch returns a Response object, need to call text()/json() first
+    writeln('got response object');
+    if vartype(aRes)=varUnknown then
+      Writeln('Got interface valued variant');
+    aUnknown:=aRes;
+    Writeln('Got interface from variant');
+    aObject:=aUnknown as IJSObject;
+    Writeln('Got IJSObject interface from variant');
+    res := TJSResponse.Cast(aObject);
+    Writeln('Got TJSResponse interface from IJSObject');
+    Writeln('request text');
+    res.text._then(@LoadJsonOK);
+    Writeln('Done requesting text');
+  except
+    On E : Exception do
+      begin
+      Writeln('Exception : ',E.ClassName,' : ',E.Message);
+      //something went wrong, free
+      Free;
+      end;
+  end;
+end;
+
+function TLoadHelper.LoadJsonOK(const aRes: Variant): Variant;
+
+var
+  S : String;
+
+begin
+  writeln('got text result. Dumping stringlist');
+  if vartype(aRes) = varOleStr then
+    begin
+    FStrings.Text:=varToStr(aRes);
+    Writeln('----');
+    for S in FStrings do
+      Writeln(S);
+    Writeln('----');
+    Writeln('Normally you would have a callback here to indicate the text is loaded');
+    end;
+  Free;
+end;
+
+{ TStringsHelper }
+
+procedure TStringsHelper.LoadFromURL(const aURL: string);
+begin
+   with TLoadHelper.Create(aURL, Self) do
+    LoadFromURL;
+end;
+
+{ TApp }
+
+procedure TApp.Run;
+begin
+  try
+    sl := TStringList.Create;
+    sl.LoadFromURL('lorem.txt');
+  except
+    on E: Exception do
+      Writeln(e.Message);
+  end;
+end;
+
+var
+  App : TApp;
+begin
+  JSWindow:=TJSWindow.JOBCreateGlobal('window');
+  App:=TApp.Create;
+  App.Run;
+end.

packages/wasm-job/examples/fetch/lorem.txt

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+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. 
+Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. 
+Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. 
+Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.