JavaScript in Android

Is it possible to use JavaScript in Android?? if so, how? Please p开发者_Python百科rovide some examples.

Thanks.

I am way late to the party here, but I had this exact need. iOS 7 now includes JavaScriptCore natively and it is really easy to use (despite limited documentation). The problem is that I didn't want to use it unless I could also use something similar on Android. So I created the AndroidJSCore project. It allows you to use your JavaScript code natively in Android without requiring a bulky WebView and injection. You can also seamlessly make asynchronous calls between Java and Javascript.

Update 27 Mar 17: AndroidJSCore has been deprecated in favor of LiquidCore. LiquidCore is based on V8 rather than JavascriptCore, but works essentially same. See the documentation on using LiquidCore as a raw Javascript engine.

From the documentation:

... to get started, you need to create a JavaScript JSContext. The execution of JS code occurs within this context, and separate contexts are isolated virtual machines which do not interact with each other.

JSContext context = new JSContext();

This context is itself a JavaScript object. And as such, you can get and set its properties. Since this is the global JavaScript object, these properties will be in the top-level context for all subsequent code in the environment.

context.property("a", 5);
JSValue aValue = context.property("a");
double a = aValue.toNumber();
DecimalFormat df = new DecimalFormat(".#");
System.out.println(df.format(a)); // 5.0

You can also run JavaScript code in the context:

context.evaluateScript("a = 10");
JSValue newAValue = context.property("a");
System.out.println(df.format(newAValue.toNumber())); // 10.0
String script =
    "function factorial(x) { var f = 1; for(; x > 1; x--) f *= x; return f; }\n" +
    "var fact_a = factorial(a);\n";
context.evaluateScript(script);
JSValue fact_a = context.property("fact_a");
System.out.println(df.format(fact_a.toNumber())); // 3628800.0

You can also write functions in Java, but expose them to JavaScript:

JSFunction factorial = new JSFunction(context,"factorial") {
    public Integer factorial(Integer x) {
        int factorial = 1;
        for (; x > 1; x--) {
            factorial *= x;
        }
        return factorial;
    }
};

This creates a JavaScript function that will call the Java method factorial when called from JavaScript. It can then be passed to the JavaScript VM:

context.property("factorial", factorial);
context.evaluateScript("var f = factorial(10);")
JSValue f = context.property("f");
System.out.println(df.format(f.toNumber())); // 3628800.0

Do you mean something like making a native app using Javascript? I know there are tools like Titanium Mobile that let you make native apps using web tools/languages.

You could also make Web Apps. There are loads of resources and tutorials out there for that. Just search "Android Web App tutorial" or something similar.

Yes you can, just create a wrap up code that points to html page and includes your javascript and css.

There are different libraries that can help you with this:

• http://www.phonegap.com/
• http://www.sencha.com/products/touch/
• http://jquerymobile.com/

Just posting this for posterity but React Native is a great solution in this space. You can write a complete app in JS using native views under the hood, or embed a JS component inside an existing Java app. https://reactnative.dev/