flutter_js_engine 1.1.1

A lite javascript engine.

JsEngine

JsEngine is a JavaScript extension based on the webview_flutter plugin's built-in JS Runtime. It allows dynamic execution of JavaScript scripts and is more lightweight compared to third-party libraries like flutter_js. It does not require additional size, supports JS HTTP network requests, SP data persistence, and promises. As it is implemented based on the WebView kernel, it can pass Google and AppStore reviews.

HTTP Requests

JsEngine has built-in network request interfaces that support promise syntax.

JS HTTP Request Example:

HttpSender.sendRequest("https://www.baidu.com/s", null, null, {
                  "wd": "%E6%97%A5%E5%8E%86"
              }, "GET").then((value) =>{
                console.log("sendRequest ok: ", value);
                run_callback(value);  // Return data to Dart layer
              });

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Data Storage

JsEngine supports persistent data storage in a key-value format, also supporting promise syntax.

JS Store and Retrieve Data Example:

SpStorage.set("ijk", "oh yep");
SpStorage.get("ijk").then((value) =>{
    console.log("SpStorage got ijk promise value:", value);
});

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Parameter Passing

⚠️ JsEngine uses variables with the 'run_' prefix as built-in global variables.

Interfaces pass parameters via params, which can be accessed in JS scripts through the built-in run_params:

JsEngine.runCode('console.log("run_params:", run_params);', params: 'dadada');
Accessing parameters in JS:

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console.log("run_params:", run_params);

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Runtime Information

Retrieve JS runtime environment information:

JsEngine.runCode('console.log("run_info:", run_info['system']);');

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Supported information includes:

Field Name	Definition
system	System
system_ver	System Version
locale	Language Code
engine_ver	Engine Version

Preload Global Library

By default, JsEngine.runCode() runs in an isolated environment, but JsEngine also supports a global mode:

JsEngine.loadLib('');

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Proxy Log Output

Proxy logs allow JS logs to be output to the Dart layer:

JsEngine.setLogProxy((tag, log) {
  print('$tag: $log');
});

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JS Call:

run_log("hello world!");

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Complete Example

JsEngine.setDebugMode(true);
JsEngine.setLogProxy((tag, log) {
  print(log);
});
JsEngine.runCode('''
          console.log("run_params:", run_params);
          console.log("run_info:", run_info['system']);
          HttpSender.sendRequest("https://www.baidu.com/s", null, null, {
                  "wd": "%E6%97%A5%E5%8E%86"
              }, "GET").then((value) =>{
                console.log("sendRequest ok: ", value);
                run_callback(value);
              });
          SpStorage.set("abc", "என்ன Yogi இப்படி சொல்லிட்ட |");
          SpStorage.set("ijk", "oh yep");
          SpStorage.get("abc").then((value) =>{
            console.log("SpStorage got abc promise value:", value);
          });
          SpStorage.get("ijk").then((value) =>{
            console.log("SpStorage got ijk promise value:", value);
          });
        ''', params: 'dadada', callback: (json) {
      logI('JsEngine-console runJsCode res: $json');
    }).then((json) {
      logI('JsEngine-console future runJsCode res: $json');
    });

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Author: Ruilin.z