When we declare a generator function with argument this argument will be passed only once when we execute the function and it returns iterator, and will be available during all calls of`next`

function*myGeneratorFunction(x) {

console.log(x);

yield x;

}

constmyIterable1=myGeneratorFunction();

constmyIterable2=myGeneratorFunction(22);

myIterable1.next();// undefined { value: undefined, done: false }

myIterable2.next();// 22 { value: 22, done: false}

The rule of arguments passed to`next` method is that, the argument will replace the previous`yield` expression, this means that passing an argument to the first`next` call will simply be ignored!

function*myGeneratorFunction() {

constx=yield1;

console.log(`x =${x}`);

consty=yield2;

console.log(`y =${y}`);

}

constmyIterable=myGeneratorFunction();

console.log(myIterable.next());

console.log(myIterable.next());

console.log(myIterable.next());

As we can see from previous example, both values`x` and`y` are`undefined` because whenever we call`next` (starting from second call of`next`) the previous yield will be set to that argument, and since we don't pass anything the previous yield is set to`undefined`

This is a copy of example 14.6 but we will make sure to pass values while calling`next` method

function*myGeneratorFunction() {

constx=yield1;

console.log(`x =${x}`);

consty=yield2;

console.log(`y =${y}`);

}

constmyIterable=myGeneratorFunction();

console.log(myIterable.next(22));

console.log(myIterable.next(33));

console.log(myIterable.next(44));

As we can see from previous example

1. 22 passed in first`next` call is completely ignored

2. 33 replaced the entire previous`yield 1` expression which means x is set to 33

3. 44 replaced the entire previous`yield 2` expression which means y is set to 44

From previous example we can also track easily the behaviour of generator function execution and where exactly it will pause.

1. on execution of this line`myIterable.next(22)` generator function will`yield 1` and pause execution, even the assignment of x is not done

2. on execution of this line`myIterable.next(33)` generator function will assign`33` to`x` and will`yield 2` and pause, even the assignment of y is not done

3. on execution of this line`myIterable.next(44)` generator function will assign`44` to`y` and will return`{ value: undefined, done : true}`