Code to Detect Java vs JavaScript Differences

Are Java and JavaScript the same? These code snippets will help you identify and understand the fundamental differences between these two distinct programming languages through practical examples.

Language Detection Utilities #

1. JavaScript Runtime Environment Detection #

// Detect if code is running in JavaScript environment
function detectJavaScriptEnvironment() {
    const environment = {
        isBrowser: typeof window !== 'undefined',
        isNode: typeof process !== 'undefined' && process.versions && process.versions.node,
        hasDOM: typeof document !== 'undefined',
        language: 'JavaScript'
    };
    
    console.log('Environment detected:', environment);
    return environment;
}

// Usage
detectJavaScriptEnvironment();

2. JavaScript-Specific Feature Detection #

// Features that prove this is JavaScript, not Java
function detectJavaScriptFeatures() {
    const features = {
        dynamicTyping: (() => {
            let variable = "string";
            variable = 42;
            variable = true;
            return "Dynamic typing works!";
        })(),
        
        prototypeChain: typeof Object.prototype !== 'undefined',
        
        firstClassFunctions: typeof function(){} === 'function',
        
        asyncAwait: typeof async function(){} === 'function',
        
        templateLiterals: `This is ${'JavaScript'}`,
        
        destructuring: (() => {
            const [a, b] = [1, 2];
            return { a, b };
        })()
    };
    
    console.log('JavaScript-specific features:', features);
    return features;
}

// Usage
detectJavaScriptFeatures();

Syntax Comparison Code #

3. Variable Declaration Differences #

4. Function Declaration Comparison #

// JavaScript function examples (multiple ways)
function traditionalFunction(name) {
    return `Hello, ${name}!`;
}

const arrowFunction = (name) => `Hello, ${name}!`;

const functionExpression = function(name) {
    return `Hello, ${name}!`;
};

// JavaScript: Functions are first-class objects
const functionArray = [traditionalFunction, arrowFunction, functionExpression];
console.log("Functions in array:", functionArray.length);

5. Object Creation Differences #

Language Feature Detectors #

6. Type System Comparison #

// JavaScript type checking utilities
function analyzeJavaScriptTypes() {
    const examples = {
        string: "Hello World",
        number: 42,
        boolean: true,
        object: {key: "value"},
        array: [1, 2, 3],
        function: function() {},
        undefined: undefined,
        null: null
    };
    
    const typeAnalysis = {};
    
    for (const [key, value] of Object.entries(examples)) {
        typeAnalysis[key] = {
            typeof: typeof value,
            constructor: value?.constructor?.name,
            isArray: Array.isArray(value),
            truthyValue: !!value
        };
    }
    
    console.log("JavaScript type analysis:", typeAnalysis);
    return typeAnalysis;
}

// Usage
analyzeJavaScriptTypes();

7. Runtime Behavior Detection #

Quick Detection Function #

8. All-in-One Language Detector #

// Comprehensive JavaScript detection utility
function confirmThisIsJavaScript() {
    const checks = {
        // Language name
        language: "JavaScript",
        
        // Runtime checks
        hasWindow: typeof window !== 'undefined',
        hasDocument: typeof document !== 'undefined',
        hasConsole: typeof console !== 'undefined',
        
        // Language features
        supportsDynamicTyping: (() => {
            let test = 1;
            test = "string";
            return typeof test === "string";
        })(),
        
        supportsClosures: typeof (function() {
            return function() {};
        })() === "function",
        
        supportsPrototypes: typeof Object.prototype === "object",
        
        // Syntax features
        supportsTemplateLiterals: `${"template"} literals work`,
        supportsDestructuring: (() => {
            try {
                const [a] = [1];
                return true;
            } catch {
                return false;
            }
        })(),
        
        // Version indicator
        ecmaScriptVersion: "ES2015+" // Modern JavaScript
    };
    
    console.log("Language confirmation:", checks);
    
    if (checks.language === "JavaScript") {
        console.log("✅ Confirmed: This is JavaScript, NOT Java!");
    }
    
    return checks;
}

// Usage
confirmThisIsJavaScript();

Usage Instructions #

These code snippets help answer "Are Java and JavaScript the same?" by demonstrating JavaScript-specific features that don't exist in Java:

1. Dynamic typing: Variables can change types
2. Prototype-based inheritance: Objects can be modified at runtime
3. First-class functions: Functions are values
4. Event-driven programming: Async operations with callbacks
5. Flexible syntax: Multiple ways to accomplish the same task

Integration Example #

// Complete detection script
if (typeof module !== 'undefined' && module.exports) {
    // Node.js environment
    module.exports = {
        detectJavaScriptEnvironment,
        detectJavaScriptFeatures,
        confirmThisIsJavaScript
    };
} else {
    // Browser environment
    window.JavaScriptDetector = {
        detectEnvironment: detectJavaScriptEnvironment,
        detectFeatures: detectJavaScriptFeatures,
        confirm: confirmThisIsJavaScript
    };
}

These utilities definitively prove that this code is running in JavaScript, not Java, helping clarify that Java and JavaScript are completely different programming languages.

For more detailed comparisons, see our Java vs JavaScript Confusion Guide.