將值傳送到生成器

可以通過將值傳遞給 next() 方法將值傳送到生成器。

function* summer() {
    let sum = 0, value;
    while (true) {
        // receive sent value
        value = yield;
        if (value === null) break;

        // aggregate values
        sum += value;
    }
    return sum;
}
let generator = summer();

// proceed until the first "yield" expression, ignoring the "value" argument
generator.next();

// from this point on, the generator aggregates values until we send "null"
generator.next(1);
generator.next(10);
generator.next(100);

// close the generator and collect the result
let sum = generator.next(null).value;  // 111