Most effective method for streamlining conditional checks in JavaScript

Question

Most effective method for streamlining conditional checks in JavaScript

To enhance the quality of my code and improve its readability, I have decided to implement a currying functions approach and create pure helper functions for repetitive code snippets. One issue I noticed was the frequent existence/type checks throughout my project in order to prevent potential errors like 'type of undefined'.

These checks typically look like:

if (param){
 action...
}

As a solution, I am considering developing a global helper function that takes two parameters; the 'param' to be checked and the 'action function' to execute if the check passes. The function will resemble this structure:

function isExist(param, action){
  if (param){
    action();
  }
}

However, this function may not be suited for all scenarios. How can I optimize it to work efficiently and universally across different cases? Moreover, I would appreciate insights on whether this approach is appropriate or if there is a superior method to achieve my objective here?

Example:

if (userInput){
  saveToDB(userInput);
}
if (valueFromDB){
  performSomeAction();
}
if (username && password){
  validate(username, password)
}

I aim to replace these separate checks at various points in my code with a single helper function, as shown below:

isExist( userInput, saveToDB(userInput) );
isExist( valueFromDB, performSomeAction );
isExist( (username && password), validate(username, password) );

This transformation condenses nine lines of code into just three, which aligns with my desired outcome.

javascript optimization functional-programming parameter-passing purely-functional

Answer 1

Answer №1

When considering a suitable name for a particular function, one potential option could be

conditionalExecute(condition, codeToExecute)

. This concept may seem familiar, but it begs the question of whether it's just an elaborate way to reinvent the if-statement itself.

From my perspective, I fail to see the advantage of overcomplicating the logic behind the if-statement beyond its current form.

Update: In the realm of Javascript, a basic conditional expression like

if(someVariable){
  // do something
}

essentially translates to "If someVariable is truthy (where undefined falls short) then...."

If your aim is solely to verify existence (as in ensuring a variable isn't undefined), then perhaps it's more effective to have a clearly defined named function for that purpose.

In this scenario, concentrating on the exact checking process rather than the conditional aspect may prove beneficial since the if-statement already handles that. For instance:

function exists(x) {
  return x !== undefined; // or a similar condition
}
function isNotNull(x) {
  // implementation pending
}

This way, your code becomes more explicit and readable, allowing for potential combination of functions like so:

function neitherUndefinedNorNull(x){
   return exists(x) && isNotNull(x);
}

if(neitherUndefinedNorNull(X)){
  // regular code execution here
}

If the block inside the if-statement is repetitive, consider extracting it into a separate function as well.

function myRepeatedCode() {
   // perform necessary actions
}

function someAlternativeCondition(x){ 
  // evaluate conditions
}

if(neitherUndefinedNorNull ){
  myRepeatedCode();
} else if(someAlternativeCondition(x)) {
  myRepeatedCode();
}

// Alternatively, combine both conditions in a single if-statement
if(neitherUndefinedNorNull(x) || someAlternativeCondition(x)){
  myRepeatedCode();
}

Final note: To save characters, you could optimize by writing

// given short-circuiting behavior, myFunc1 and myFunc2 only execute
// when myCond1 and myCond2 are true (or truthy).
myCond1(x) && myFunc1(x)
myCond2(y) && myFunc2(y)

Answer 2

When considering a suitable name for a particular function, one potential option could be

conditionalExecute(condition, codeToExecute)

. This concept may seem familiar, but it begs the question of whether it's just an elaborate way to reinvent the if-statement itself.

From my perspective, I fail to see the advantage of overcomplicating the logic behind the if-statement beyond its current form.

Update: In the realm of Javascript, a basic conditional expression like

if(someVariable){
  // do something
}

essentially translates to "If someVariable is truthy (where undefined falls short) then...."

If your aim is solely to verify existence (as in ensuring a variable isn't undefined), then perhaps it's more effective to have a clearly defined named function for that purpose.

In this scenario, concentrating on the exact checking process rather than the conditional aspect may prove beneficial since the if-statement already handles that. For instance:

function exists(x) {
  return x !== undefined; // or a similar condition
}
function isNotNull(x) {
  // implementation pending
}

This way, your code becomes more explicit and readable, allowing for potential combination of functions like so:

function neitherUndefinedNorNull(x){
   return exists(x) && isNotNull(x);
}

if(neitherUndefinedNorNull(X)){
  // regular code execution here
}

If the block inside the if-statement is repetitive, consider extracting it into a separate function as well.

function myRepeatedCode() {
   // perform necessary actions
}

function someAlternativeCondition(x){ 
  // evaluate conditions
}

if(neitherUndefinedNorNull ){
  myRepeatedCode();
} else if(someAlternativeCondition(x)) {
  myRepeatedCode();
}

// Alternatively, combine both conditions in a single if-statement
if(neitherUndefinedNorNull(x) || someAlternativeCondition(x)){
  myRepeatedCode();
}

Final note: To save characters, you could optimize by writing

// given short-circuiting behavior, myFunc1 and myFunc2 only execute
// when myCond1 and myCond2 are true (or truthy).
myCond1(x) && myFunc1(x)
myCond2(y) && myFunc2(y)

Answer 3

Answer №2

If you're searching for the ideal opportunity to utilize Maybe, then look no further:

const enumerable = true;

// data Maybe a = Nothing | Just a

const Maybe   = {};
const Nothing = Object.create(Maybe);
const Just    = value => Object.create(Maybe, {value: {enumerable, value}});

// instance Functor Maybe where

Nothing.map = _ => Nothing;
Maybe.map = function (fun) { return Just(fun(this.value)); };

// instance Applicative Maybe where

Maybe.of = Just;
Nothing.ap = _ => Nothing;
Maybe.ap = function (maybe) { return maybe.map(this.value); };

// instance Monad Maybe where

Nothing.chain = _ => Nothing;
Maybe.chain = function (kleisli) { return kleisli(this.value); };

Maybe ~~follows the Fantasy Land Specification~~^[1]. By incorporating Maybe into your code, you can craft functionalities like these:

// userInput :: Maybe Data
// saveToDB  :: Data -> Something
userInput.map(saveToDB); // :: Maybe Something

// valueFromDB       :: Maybe Data
// performSomeAction :: Data -> Maybe Something
valueFromDB.chain(performSomeAction); // :: Maybe Something

// username :: Maybe String
// password :: Maybe Password
// validate :: String -> Password -> Something
Maybe.of(validate).ap(username).ap(password); // :: Maybe Something

For those truly intrigued by functional programming, I recommend diving into Learn You A Haskell.

^[1] While discussing the Fantasy Land Specification, there is a disagreement regarding flipping the arguments of ap.

Answer 4

If you're searching for the ideal opportunity to utilize Maybe, then look no further:

const enumerable = true;

// data Maybe a = Nothing | Just a

const Maybe   = {};
const Nothing = Object.create(Maybe);
const Just    = value => Object.create(Maybe, {value: {enumerable, value}});

// instance Functor Maybe where

Nothing.map = _ => Nothing;
Maybe.map = function (fun) { return Just(fun(this.value)); };

// instance Applicative Maybe where

Maybe.of = Just;
Nothing.ap = _ => Nothing;
Maybe.ap = function (maybe) { return maybe.map(this.value); };

// instance Monad Maybe where

Nothing.chain = _ => Nothing;
Maybe.chain = function (kleisli) { return kleisli(this.value); };

Maybe ~~follows the Fantasy Land Specification~~^[1]. By incorporating Maybe into your code, you can craft functionalities like these:

// userInput :: Maybe Data
// saveToDB  :: Data -> Something
userInput.map(saveToDB); // :: Maybe Something

// valueFromDB       :: Maybe Data
// performSomeAction :: Data -> Maybe Something
valueFromDB.chain(performSomeAction); // :: Maybe Something

// username :: Maybe String
// password :: Maybe Password
// validate :: String -> Password -> Something
Maybe.of(validate).ap(username).ap(password); // :: Maybe Something

For those truly intrigued by functional programming, I recommend diving into Learn You A Haskell.

^[1] While discussing the Fantasy Land Specification, there is a disagreement regarding flipping the arguments of ap.

Answer 5

Answer №3

How about this? It has the ability to process multiple parameters simultaneously.

function test(a,b,c)
{
    console.log("%s,%s,%s",a,b,c)
}

function check_and_run(param,action){
    var args = Array.prototype.slice.call(arguments);
    args.shift();
    args.shift();
    if(param)
        action.apply(this,args)  
}


check_and_run(1,test,1,2,3)  //this will invoke test(1,2,3)
check_and_run(0,test,1,2,3)  //this will do nothing

Answer 6

How about this? It has the ability to process multiple parameters simultaneously.

function test(a,b,c)
{
    console.log("%s,%s,%s",a,b,c)
}

function check_and_run(param,action){
    var args = Array.prototype.slice.call(arguments);
    args.shift();
    args.shift();
    if(param)
        action.apply(this,args)  
}


check_and_run(1,test,1,2,3)  //this will invoke test(1,2,3)
check_and_run(0,test,1,2,3)  //this will do nothing

Answer 7

Answer №4

Maybe you can use a function like this:

function conditionFunction(condition, callbackFunction, defaultResult=undefined) {
  return (...args) => {
    if (condition(...args)) {
      return callbackFunction(...args);
    }
    return defaultResult;
  }
}

const add = conditionFunction(
   (...args) => args.every(num => typeof num === 'number'),
   (...args) => args.reduce((total, num) => total + num), 
   NaN);

add("1", "2"); //=> NaN
add(1, 2);     //=> 3

If you want to make sure that the first argument is not undefined:

const firstDefined = (value) => typeof value !== 'undefined';
const conditionalSomeFunction = conditionFunction(firstDefined, someFunction, "");

conditionalSomeFunction(); // ==> ""
conditionalSomeFunction("test"); // ==> whatever someFunction("test") returns

If your goal is to call a function only when all arguments are defined, you can do it simply like this:

function callIfDefined(func, ...args) {
  if (args.every(firstDefined)) {
    return func(...args);
  }
  return undefined;
}

callIfDefined(saveToDatabase.bind(this, userInput), userInput);
callIfDefined(performAction, valueFromDatabase);
callIfDefined(validate.bind(this, username, password), username, password);

Answer 8

Maybe you can use a function like this:

function conditionFunction(condition, callbackFunction, defaultResult=undefined) {
  return (...args) => {
    if (condition(...args)) {
      return callbackFunction(...args);
    }
    return defaultResult;
  }
}

const add = conditionFunction(
   (...args) => args.every(num => typeof num === 'number'),
   (...args) => args.reduce((total, num) => total + num), 
   NaN);

add("1", "2"); //=> NaN
add(1, 2);     //=> 3

If you want to make sure that the first argument is not undefined:

const firstDefined = (value) => typeof value !== 'undefined';
const conditionalSomeFunction = conditionFunction(firstDefined, someFunction, "");

conditionalSomeFunction(); // ==> ""
conditionalSomeFunction("test"); // ==> whatever someFunction("test") returns

If your goal is to call a function only when all arguments are defined, you can do it simply like this:

function callIfDefined(func, ...args) {
  if (args.every(firstDefined)) {
    return func(...args);
  }
  return undefined;
}

callIfDefined(saveToDatabase.bind(this, userInput), userInput);
callIfDefined(performAction, valueFromDatabase);
callIfDefined(validate.bind(this, username, password), username, password);

Most effective method for streamlining conditional checks in JavaScript

Answer №1

Answer №2

Answer №3

Answer №4

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