Pure functions and usage in Angular

Pure functions and usage in Angular

• 1.
  Pure function: concepts& cases Mike MA 594mjf@gmail.com
• 2.
  What is purefunction
• 3.
  Concept A pure functionis a function where the return value is only determined by its input values, without observable side effects. ● When given the same argument, the result will always be the same ● Pure functions do not produce side effects. ● Foundation of functional programming
• 4.
  Reproducible Result function half(x){ return x / 2; }i Pure functions only depend on what's passed to them When invoked, a pure function can be replaced by its result. This is called referential transparency.
• 5.
  No Side Effect functionhalf(x) { return x / 2; }i When a function or expression modifies state outside its own context, the result is a side effect. Making a call to an API, manipulating the DOM, raising an alert dialog, writing to a database, etc.
• 6.
  Benefits: why usepure function?
• 7.
  Portable/Reusable Only depends oninput, easy to copy to somewhere else The problem of OOP: You wanted a banana but what you got was a gorilla holding the banana and the entire jungle.
• 8.
  Easy to refactorand test Pure functions are also extremely independent — easy to move around, refactor, and reorganize in your code, making your programs more flexible and adaptable to future changes. Given predictable result
• 9.
  Easy to combine/parallelizethem An Example of Functional Programming (FP):
• 10.
  Memoization (cacheable) You maycache the output for a given input.
• 11.
  In real practice: purepipe in Angular
• 12.
  Pipe API Angular executesa pure pipe only when it detects a pure change to the input value. A pure change is either a change to a primitive input value (String, Number, Boolean, Symbol) or a changed object reference (Date, Array, Function, Object). A pure pipe uses pure functions. Pure functions process inputs and return values without detectable side effects. Given the same input, they should always return the same output.
• 15.
  Why pure pipeis recommended? Let’s see some real code … https://codepen.io/simars/pe n/wxRpjN?editors=0010#0
• 16.
  Thanks!