[Javascript] Intro to Recursion - Detecting an Infinite Loop-优快云博客

本文探讨了在使用递归函数时如何避免无限循环的问题，通过引入parents数组记录已访问的顶级命令，确保程序能够正确处理重复配置项，避免陷入无限循环。

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When using recursion, you must be mindful of the dreaded infinite loop. Using the recursive function that we’ve built up over the previous lessons, we look at how a simple duplicated configuration item could cause chaos for our program as it has no context of which items it has previously seen. We fix this problem by introducing a parents array, which can keep track of which top-level commands have already been accessed.

let input, config;

input = ['dist'];

config = {
  "dist": ["build", "deploy"],
  "build": ['js', 'css', 'vender'],
  "js": ['babel', 'ng-Annotate', "uglify"],
  "css": ["sass", "css-min"]
};

var res = getTasks(config, input, []);

function getTasks(config, input, initial){
  
  return input.reduce((prev, next)=>{
    if(config[next]){
      return getTasks(config ,config[next], prev);
    }else{
      return prev.concat(next);
    }
  }, initial);
};

console.log(res);

----------

Code:

let input, config;

input = ['dist'];

config = {
  "dist": ["build", "deploy"],
  "build": ['js', 'css', 'vender', 'dist'],
  "js": ['babel', 'ng-Annotate', "uglify"],
  "css": ["sass", "css-min"]
};

var res = getTasks(config, input);

function getTasks(config, input, initial, parent){
  
  initial = initial || [];
  parent = parent || [];
  
  return input.reduce((prev, next)=>{
    
    if(parent.indexOf(next) > -1){
      console.log('infinite loop detected!');
      return prev;
    }
    
    if(config[next]){
      return getTasks(config ,config[next], prev, parent.concat(next));
    }else{
      return prev.concat(next);
    }
  }, initial);
};

console.log(res);