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javascriptfunctiongeneratorecmascript-6ecmascript-harmony

What is the difference between function and function*


What is the difference between generator functions created with function and function*

function a(i){
    for(;i>0;i--){
        yield i*i;
    }
}
function *b(i){
    for(;i>0;i--){
        yield i*i*i;
    }
}

Solution

  • Generators created with function are part of earlier ES6 draft.

    //They have differrent prototypes
    console.log(a.prototype.constructor.constructor,b.prototype.constructor.constructor);//function Function() function GeneratorFunction()
    let a1=a(10);
    let b1=b(10);
    //both create generators...
    console.log(a1,b1);//Generator {  } Generator {  }
    //but different generators: one returns value, another returns an object of special format
    console.log(a1.next(),b1.next());//100 Object { value: 1000, done: false }
    for(let a2 of a1)console.log(a2);
    for(let b2 of b1)console.log(b2);
    //They are equal when used in for ... of.