mrhampson · August 9, 2018 18:33
diff --git a/defaultParamsOveruseExample.ts b/defaultParamsOveruseExample.ts
 /**
 I created this gist to point out something I consider a bad practice that I've seen in typescript code:
 that is overuse of default parameters. The problem with overusing default parameters is that the default behavior
 of the function without args is completely implicit and requires the developer to reference the function definition and
 memorize whenever they are looking through the code.

 In the examples below I took some of our existing code that had such a function retrieveData where its behavior 
 was hidden behind default parameters. I refactored it by using functions that are named something descriptive that 
 then call retrieveData with the appropriate parameters. By providing a function with a descriptive name rather than 
 letting parameter default it is much clearer what the code is doing when you are far away from the retrieveData 
 function definition.

 To be clear, I'm not suggesting default parameters should never be used. In certain situations they can make things 
 clearer and save repeated code. 
 */

 /***************************************************************
 * Before refactor 
 ***************************************************************/

 private retrieveData(activeOnly = true, inactiveOnly = false) {
  // gets data
 }

 // Later on 
 // What is this doing? No idea without having memorize the function definition further up.
 // This boolean condition is also copy/pasted multiple times
 this.retrieveData(this.$scope.activeTabsAlerts.id === LaAlerting.ACTIVE_TAB.id);

 // Later on 
 // Same problem: no idea what this means. Entirely implicit and relys on the developer memorizing the definition
 this.retrieveData(true)

 /***************************************************************
 * After refactor 
 ***************************************************************/
 // The functions below replace the original function with default parameters

 // By putting the logic for which tab gets what data in this function rather than copy/pasteing a conditional statement 
 // that evaluates to the activeOnly paramter we avoid copy/paste code of the conditional and make the logic clearer
 // and less prone to mistakes
 private getDataForTabId(tabId) {
  if (tabId === LaAlerting.ACTIVE_TAB.id) {
    this.retrieveOnlyActiveAlerts();
  }
  else {
    this.retrieveAlerts();
  }
 }

 private retrieveOnlyActiveAlerts() {
  return this.retrieveData(true, false);
 }

 private retrieveAlerts() {
  return this.retrieveData(false, false);
 }

 private retrieveData(activeOnly:boolean, inactiveOnly:boolean) {
  // gets data
 }

 // Later on in code 
 // No repeated boolean logic 
 this.getDataForTabId(this.$scope.activeTabsAlerts.id);

 // Later on in code
 // Code is self describing and says what it does
 this.retrieveOnlyActiveAlerts();
	/**
	I created this gist to point out something I consider a bad practice that I've seen in typescript code:
	that is overuse of default parameters. The problem with overusing default parameters is that the default behavior
	of the function without args is completely implicit and requires the developer to reference the function definition and
	memorize whenever they are looking through the code.

	In the examples below I took some of our existing code that had such a function retrieveData where its behavior
	was hidden behind default parameters. I refactored it by using functions that are named something descriptive that
	then call retrieveData with the appropriate parameters. By providing a function with a descriptive name rather than
	letting parameter default it is much clearer what the code is doing when you are far away from the retrieveData
	function definition.

	To be clear, I'm not suggesting default parameters should never be used. In certain situations they can make things
	clearer and save repeated code.
	*/

	/***************************************************************
	* Before refactor
	***************************************************************/

	private retrieveData(activeOnly = true, inactiveOnly = false) {
	// gets data
	}

	// Later on
	// What is this doing? No idea without having memorize the function definition further up.
	// This boolean condition is also copy/pasted multiple times
	this.retrieveData(this.$scope.activeTabsAlerts.id === LaAlerting.ACTIVE_TAB.id);

	// Later on
	// Same problem: no idea what this means. Entirely implicit and relys on the developer memorizing the definition
	this.retrieveData(true)

	/***************************************************************
	* After refactor
	***************************************************************/
	// The functions below replace the original function with default parameters

	// By putting the logic for which tab gets what data in this function rather than copy/pasteing a conditional statement
	// that evaluates to the activeOnly paramter we avoid copy/paste code of the conditional and make the logic clearer
	// and less prone to mistakes
	private getDataForTabId(tabId) {
	if (tabId === LaAlerting.ACTIVE_TAB.id) {
	this.retrieveOnlyActiveAlerts();
	}
	else {
	this.retrieveAlerts();
	}
	}

	private retrieveOnlyActiveAlerts() {
	return this.retrieveData(true, false);
	}

	private retrieveAlerts() {
	return this.retrieveData(false, false);
	}

	private retrieveData(activeOnly:boolean, inactiveOnly:boolean) {
	// gets data
	}

	// Later on in code
	// No repeated boolean logic
	this.getDataForTabId(this.$scope.activeTabsAlerts.id);

	// Later on in code
	// Code is self describing and says what it does
	this.retrieveOnlyActiveAlerts();