(TypeError): Blob is not a constructor

Question

This code when called under Firefox/Windows it works fine, however, when called from Firefox/Linux it throws the error below:

private native String getBlobUrl(String b64)/*-{
    function base64ToBlob(base64) {
        var binary = atob(base64);
        var len = binary.length;
        var buffer = new ArrayBuffer(len);
        var view = new Uint8Array(buffer);
        for ( var i = 0; i < len; i++) {
                view[i] = binary.charCodeAt(i);
        }
        var blob = new Blob([ view ]);
        return blob;
    };
    var newBlob = base64ToBlob(b64);
    var URLObj = window.URL || window.webkitURL;
    var source = URLObj.createObjectURL(newBlob);
    return source;
}-*/;

Error:

00:06:08.107 [ERROR] Uncaught exception escaped com.google.gwt.core.client.JavaScriptException: (TypeError): Blob is not a constructor at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:248) at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136) at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561) at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269) at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91) at com.google.gwt.core.client.impl.Impl.apply(Impl.java) at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213) at sun.reflect.GeneratedMethodAccessor73.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103) at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71) at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172) at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:292) at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:546) at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363) at java.lang.Thread.run(Thread.java:722)

What could be wrong in my code?

I think the error is within this line (yet it works fine under Windows environment):

var blob = new Blob([ view ]);

Answer 1

In gwt jsni methods you need to use "$wnd." prefixes instead of "window.". Note, that atob() is actually window.atob(). You need to add this prefix for all window.xxx methods in your jsni code (before "atob(base64)", "URL" and "webkitUrl") :

private native String getBlobUrl(String b64)/*-{
    function base64ToBlob(base64) {
        var binary = $wnd.atob(base64);
        var len = binary.length;
        var buffer = new ArrayBuffer(len);
        var view = new Uint8Array(buffer);
        for (var i = 0; i < len; i++) {
            view[i] = binary.charCodeAt(i);
        }
        var blob = new Blob([ view ]);
        return blob;
    };
    var newBlob = base64ToBlob(b64);
    var URLObj = $wnd.URL || $wnd.webkitURL;
    var source = URLObj.createObjectURL(newBlob);
    return source;
}-*/;

Good article about jsni: http://www.gwtproject.org/doc/latest/DevGuideCodingBasicsJSNI.html