[Javascript] Intro to Recursion-refactoring to a Pure Function

Previous post:http://www.cnblogs.com/answer1215/p/4990418.html

= [' dist '= {  "dist": ["Build", "deploy"],  "Build": [' js ', ' css ', ' vender '],   "js": [' Babel ', ' ng-annotate ', "uglify"],  "css": ["Sass", "css-min"= []; Gettasks (input); function gettasks (input) {    Input.foreach (Task)={    if(Config[task]) {      gettasks (Config[task]);    } Else {      Tasks.push (Task);}}  )}; Console.log (tasks);

The Gettasks works but have some problem:

• We depend on the outside variable ' tasks ' and ' config ', so there is side effect
• There is no return value, hard to test

Let input, config, Tasks;input= [' Dist '];config= {  "Dist": ["Build", "deploy"],  "Build": [' js ', ' css ', ' vender '],  "JS": [' Babel ', ' ng-annotate ', ' uglify '],  "CSS": ["Sass", "Css-min"]};tasks= [];varres =gettasks (input, []);functiongettasks (input, initial) {returnInput.reduce (prev, next) ={    if(Config[next]) {returnGettasks (Config[next], prev); }Else{      returnPrev.concat (next); }}, initial);}; Console.log (res);

The code has been improved, we return the value from the Gettasks () function and we don ' t modify the tasks array anymore.

Just One thing we still need to do are we still depend on ' config ':

Let input, Config;input= [' Dist '];config= {  "Dist": ["Build", "deploy"],  "Build": [' js ', ' css ', ' vender '],  "JS": [' Babel ', ' ng-annotate ', ' uglify '],  "CSS": ["Sass", "Css-min"]};varres =gettasks (config, input, []);functiongettasks (config, input, initial) {returnInput.reduce (prev, next) ={    if(Config[next]) {returngettasks (config, Config[next], prev); }Else{      returnPrev.concat (next); }}, initial);}; Console.log (res);

[Javascript] Intro to Recursion-refactoring to a Pure Function