Q31. What are the two property of yield in JavaScript? How we migrate to next value
Q32. How to traverse elements on HTML using JavaScript? or How to traverse DOM elements using javascript?
Q33. What are local variables and global variables in JavaScript?
Q34. What are generators in JavaScript?
Q35. What is yield in JavaScript?
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Q31. What are the two property of yield in JavaScript? How we migrate to next value
Answer 31:
"done" and "value" are the two properties present
in yield.
Initially "done" remain false till iterator object reaches the
end of object using .next() where "done" become true and "value" become
"undefined".
with the help of .next() we migrate to next value.
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Q32. How to traverse elements on HTML using JavaScript? or How to traverse DOM elements using javascript?
Answer 32:
There are multiple ways we can traverse DOM elements using javascript eg. document.querySelector is the most common way.
You can traverse in three directions:- Downwards
- Sideways
- Upwards
https://zellwk.com/blog/dom-traversals/
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Q33. What are local variables and global variables in JavaScript?
Answer 33:
JavaScript has three scopes – global, functional and block scope. Any
variable declared outside of a function belongs to the global scope, and
is therefore accessible from anywhere in your code. Each function has
its own scope, and any variable declared within that function is only
accessible from that function and any nested functions
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Q34. What are generators in JavaScript?
Answer 34:
With ES6 generators, we have a different kind of function, which may be paused in the middle, one or many times, and resumed later, allowing other code to run during these paused periods.
you use the new yield keyword to pause the function from
inside itself. Nothing can pause a generator from the outside; it pauses
itself when it comes across a yield.
However, once a generator has yield-paused itself, it cannot resume on its own. An external control must be used to restart the generator.
Even more importantly, this stopping and starting is not just a
control on the execution of the generator function, but it also enables
2-way message passing into and out of the generator, as it progresses.
With normal functions, you get parameters at the beginning and a return value at the end. With generator functions, you send messages out with each yield, and you send messages back in with each restart.
Syntax:
function *foo() { }
The way we control generator functions from the outside is to construct and interact with a generator iterator. We use is using the 'next' keyword
Good learning in below url after the heading "Generator Iterator"
https://davidwalsh.name/es6-generators
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Q35. What is yield in JavaScript?
Answer 35:
It can be thought of as a generator-based version
of the return keyword. The yield keyword actually returns an
IteratorResult object with two properties, value and done. The value
property is the result of evaluating the yield expression, and done is
false, indicating that the generator function has not fully completed.
(function(){
console.clear();
function* foo(index){
while(index <2){
yield index++;
}
}
const iterator = foo(0);
console.log(iterator.next());
console.log(iterator.next());
console.log(iterator.next());
})();
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/yield