CODEWITHSUNDEEP
javascriptsyntaxyield
Ben
Ben

Reputation: 3654

Why is yield classed as an operator and not a statement?

I was looking at the mdn javascript reference and noticed that yield is listed in the operators section. On the other hand return is listed as a statement. I also found yield has a operator precedence of 2.

What features of yield make it fall into the operator class rather than a statement? Why does return fall into statements rather than operators?

Upvotes: 5

Views: 66

Answers (2)

Nina Scholz
Nina Scholz

Reputation: 386600

It is an operator because it can be used in an expression.

function* g() {
    value = 3;
    while (value !== 5) value = Math.floor(yield value + 1);
}

var gen = g();

console.log(gen.next().value);
console.log(gen.next(1.5).value);

Upvotes: 3

akaphenom
akaphenom

Reputation: 6888

I am not certain on this, but in the context of a generator yield sends data to the generator.next() in that way it operates much like a function. Operators are special classes of functions in the most languages (JavaScript inlcuded).

You could almost imagine the generator.next calling into its instance passing a callback as to where to resume. And yield invoking that callback

Return signals the end of a path of execution and to replace a return value into the proper memory location and unwind the call stack by 1 unit. If feels primordial to the definition of the language,

Upvotes: 1

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