JavaScript vs Python 语法对比

# Python 版本
numbers = [1, 2, 3, 4, 5]
doubled = [x * 2 for x in numbers]
even_numbers = [x for x in doubled if x % 2 == 0]
sum_result = sum(even_numbers)
print(sum_result)

// JavaScript 版本
function processData(data, callback = null) {
    const result = [];
    for (const item of data) {
        let processed;
        if (callback) {
            processed = callback(item);
        } else {
            processed = item * 2;
        }
        result.push(processed);
    }
    return result;
}

// 使用示例
const numbers = [1, 2, 3, 4, 5];
const result = processData(numbers, x => x ** 2);
console.log(result);

inner x: 30
outer x: 20
global x: 10

inner x: 30
outer x: 20
global x: 10