Syntax error for: generator function parameter is unex

Question

I get confused about the syntax for generator in node environment.

I run the script as: node --harmony simpleGenerator.js, but still have problem. My node environment is Linux (v0.11.5 / v0.11.13)

Syntax Error: Unexpected identifier

/home/NodeProj/ES6-generator/simpleGenerator.js:6
        yield x;
              ^

script:

function foo(x) {
    while (true) {
        x = x * 2;
        yield x;
    }
}

var gen = foo(1);

console.log(gen.next().value);

What's going on here ?

Answer 1

A generator needs an asterisk after the function keyword:

function* foo(x) {
    while (true) {
        x = x * 2;
        yield x;
    }
}