Yield - Generator Functions

The generator functions provide a simple way to program a iterator using native resources of the java script programming language. It provide a simple syntax for blocking and continue the flow of a function executing based on interactions with this function.

It is quite useful to any function that has to process a certain dataset, but just a part by time, optimizing the processing and memory consumption.

A generator function is a normal java script function that has a “*” at the side of the function name. It means this function when being its execution is allowed to stop in a blocking way, as soon as it found the yield keyword. In this moment the value that the right of yield is returned, and the function execution is blocked until this function is called gain through the .next() method.

function* generator_function(index) {
    while (index < 2) {
      yield index;
      index++;
    }
  }

 The value at the right of yield statement can be read by the .value property.

  const iterator = generator_function(0);//seed

  console.log(iterator.next().value); // output: 0

Then it will keep executing in this way while the yield statement is found. The only way a generator function is concluded is:

a)      The function reaches its end – the undefined value is returned.

b)     The function explicitly return a value with the return keyword.

c)      Some exception is throw.

You can see on example of this code at this link:

https://github.com/rafaelqg/code/blob/main/generator_function_yield.js

A video class is also available here:



Comments

Post a Comment

Popular posts from this blog

HASHLIB: Using HASH functions MD5 and SHA256

Image
  The usage of hash functions in python is quite simple. Basically we can use the native library hashlib, which give us the possibly to create message digest based on several algorithms, such as MD5 or SHA256. Using this library we may create a hash of some content and then retrieve its binary output or transform that in hexadecimal strings to easy the data transfer in different medias. The library can be imported with the following instruction: import hashlib   If you want to encode strings, it is necessary to encode that with UTF-8, and it can be done using the encode method of a string object: myPassword= "python3.x" myPasswordEncoded=myPassword.encode( 'utf-8' )       The n, the hashlib module has a md5 function which receives as parameter the the we would like to generate the hash. And then return the hash object. hashObject=hashlib.md5(myPasswordEncoded)   The hashObject already contains the ...
Read more

Spread Operator

Image
  The spread operator can be utilized both on arrays and objects. For arrays it will transform the array in a plain list of objects/variables, which can be utilized as input to functions that accept a list of arguments (example: array.push(el1, el2, el3). In This example if we have one array named array01 with options [1,2,3] and we want to add these values to another array, named array02, then we can do array02.push(…array01). Performing that, using the spread operator (…) actually the array02 will have a copy of all elements that are inside array01. Without using the spread operator , for example, array02.push(array01), the array02 will contains one single object that is the array01 itself, and only inside array01 that the values will be found. Another applicability for spread operator is for objects itself. When we want to have a new object with contains a copy of all attributes an existing object already have, in addition to new attributes, we can use the spread operator. L...
Read more

Dart: implementing Object Oriented Programming (OOP)

Image
The object oriented programming provides several benefits for system design. It makes the code easier to maintain, easier to extends, and also implements several well-know design patterns. Using the Dart programing language classes can be simple defined utilizing the class keyword, followed by the class name, and then delimitated the class body with the key brackets {}, like in the example below, presenting one class with two methods. class ProgrammingLanguage {   void compile (){     print( "Compiling..." );   }   void execute (){     print ( "Executing..." );   } } When we need to add new features to this class, it is possible to use the inherence concept, defining a new class that will receive all implementation this ProgrammingLanguage class already has done. And this inherence is done using the extends keywork, like in the example below, which the Dart class has the compile() and the execute() methos from its superclass...
Read more