Rust Requires Chilkat v11.4.0+

JavaScript console using Callbacks

See more JavaScript Examples

Demonstrates console output using Chilkat JavaScript with callbacks. Rust

struct JsEvents;

impl chilkat::EventHandler for JsEvents {
    fn progress_info(&mut self, name: &str, value: &str) {
        println!("{}: {}", name, value);
    }
}

// This example demonstrates using the built-in console object.
// The Javascript run in this example is shown below.

// Load the JavaScript from a file.
let sb_script = chilkat::StringBuilder::new();
if sb_script.load_file("qa_data/js_tests/test_console.js", "utf-8").is_err() {
    println!("{}", sb_script.last_error_text());
    return;
}

let js = chilkat::Js::new();
js.set_event_handler(JsEvents);
let result = chilkat::JsonObject::new();

// Run the JavaScript
// Results (not console output) go to result.
// Note: Eval returns the completion value of the script. This is generally the value of the last evaluated expression.
// In this case, the last evaluated expression is console.log which does not calculate a value. Therefore, it returns undefined.
if js.eval(&sb_script, &result).is_err() {
    println!("{}", sb_script.last_error_text());
    return;
}

// We can look at the result, which is "undefined", which is normal and expected.
println!("{}", result.emit().unwrap_or_default());
// The result JSON is: {"type":"undefined","value":"undefined"}

// The console output is received using ProgressInfo callbacks.
// The output is:

// log: Hello World, 248, 12.05
// 
// error: foo:bar baz
// 
// warn: 1 2 3
// 
// log: %% %s
// 
// log: myApp: {
//   "appName": "Example",
//   "version": 1,
//   "isDebug": true,
//   "supportedTypes": [
//     "string",
//     "number",
//     "object"
//   ],
//   "settings": {
//     "maxWidgets": 1024,
//     "allowIO": true
//   }
// }
// 
// log: App: myApp (Version 1)
// 
// {"type":"undefined","value":"undefined"}

JavaScript

// Chilkat Js console emits CRLF line endings on Windows, and LF line endings on non-Windows.

console.log("Hello %s, %d, %f", "World", 248, 12.05);
// Output: Hello World, 248, 12.05

// If there are more arguments than the number of specifiers, the extra arguments are output, separated by spaces:
console.error('%s:%s', 'foo', 'bar', 'baz');
// Output: foo:bar baz

// If the first argument does not contain a valid format specifier, outputs a string that is the concatenation of all arguments separated by spaces:
console.warn(1,2,3);
// Output: 1 2 3

//If only one argument is passed, it is returned as it is without any formatting:
console.log("%% %s");
// Output: %% %s

const myApp = {
    appName: "Example",
    version: 1.0,
    isDebug: true,
    supportedTypes: ["string", "number", "object"],
    settings: {
       "maxWidgets": 1024,
        allowIO: true
    }
};

// %O: Emits the same as JSON.stringify(myConfig, null, 2)
console.log("myApp: %O", myApp);
// Output:
// myApp: {
//   "appName": "Example",
//   "version": 1,
//   "isDebug": true,
//   "supportedTypes": [
//     "string",
//     "number",
//     "object"
//   ],
//   "settings": {
//     "maxWidgets": 1024,
//     "allowIO": true
//   }
// }

console.log("App: %s (Version %d)", myApp.appName, myApp.version);
// Output: App: Example (Version 1)