javascript - 多输入一输出

Question

如何将多个输入值处理为一个输出值？

function c(input,val){
    return input.indexOf(val)>-1;   
}

function result(i){
    if(c(i,1) && c(i,2) && c(i,3)){
       return "alpha";
    }else if(c(i,1) && c(i,2) && !c(i,3)){ 
       return "beta";
    }else if(c(i,1) && !c(i,2) && c(i,3)){
       return "gamma";
    }else if(c(i,1) && !c(i,2)){ 
       return "delta";
    }else if(c(i,3)){
       return "theta";
    }
   //..... and so on covering all possible combinations

   return null;
}

result([1,2,3]);     //output : alpha
result([1,3,2]);     //output : alpha
result([1,3,1,1]);   //output : gamma
result([1,2,4]);     //output : beta
result([3]);         //output : theta

数组中的值的数量可以是 N，但只能来自一组预定义的值

处理这么多组合的正确方法是什么？

Answer 1

根据 Condor 的回答，以下内容应该可以完成工作。它使用一系列测试来计算结果并执行“不”测试。如果值为“true”，则它必须出现，如果值为“false”，则不得出现。如果未提及，则它是否在值中并不重要。

重复不是问题，值会被处理直到一个失败。不过，先删除重复项可能会加快速度。

结果是第一组通过的测试的名称。

function testValues(values) {

  var checks = [
      {alpha:  {1:true,  2:true,  3:true }},
      {beta :  {1:true,  2:true,  3:false}},
      {gamma:  {1:true,  2:false, 3:true }},
      {theta:  {3:true}}
  ];
  var check, resultName, tests, passed;

  // Do checks in sequence
  for (var i=0, iLen=checks.length; i<iLen; i++) {
    check = checks[i]

    // Get name of result to return if the checks pass
    for (resultName in check) {

      // Make sure result is own property
      if (check.hasOwnProperty(resultName)) {

        // Passed is true until a fail is found
        passed = true;

        // Get tests to perform
        tests = check[resultName];

        // For each value in tests, make sure value exists or doesn't in values
        for (var v in tests) {

          if (tests.hasOwnProperty(v)) {

            // Only test if passed is true
            if (passed) {

              // Note that indexOf uses === so must have same type
              // Property names are always strings so if passing numbers,
              // Must convert to numbers
              passed = tests[v] === (values.indexOf(+v) != -1);
            }
          }
        }

        // If passed tests, return
        if (passed) return resultName;

      }
    }
  }
  return 'failed all tests...';
}

console.log(testValues([1,2,3]));     //output : alpha
console.log(testValues([1,3,2]));     //output : alpha
console.log(testValues([1,3,1,1]));   //output : gamma
console.log(testValues([1,2,4]));     //output : beta
console.log(testValues([3]));         //output : theta

如果 Object.keys 与 forEach 一起使用，代码可能会更短一些，但上面的代码更清楚一点(也许)，它可以重构为更短。如果提供了用于 Array.prototype.indexOf 的垫片，以上内容将在 ECMA-262 ed 3 环境中工作。

编辑

如果使用现代功能，代码可以稍微简化。为旧浏览器提供支持并不困难:

// These are sufficient to support the function but are not suitable for general use
// Better versions are avaialble at MDN, see links below
if (!Object.keys) {
  Object.keys = function(obj) {
    var keys = [];
    for (var key in obj) {
      if (obj.hasOwnProperty(key)) {
        keys.push(key);
      }
    }
    return keys;
  };
}

if (!Array.prototype.indeOf) {
  Array.prototype.indexOf = function (value) {
    for (var i=0, iLen=this.length; i<iLen; i++) {
      if (this[i] === value) return i;
    }
    return -1;
  };
}

function testValues(values) {

  var checks = [
      {alpha:  {1:true,  2:true,  3:true }},
      {beta :  {1:true,  2:true,  3:false}},
      {gamma:  {1:true,  2:false, 3:true }},
      {theta:  {3:true}}
  ];
  var check, passed, resultName, tests, testKeys;

  for (var i=0, iLen=checks.length; i<iLen; i++) {
    check = checks[i]
    resultName = Object.keys(check)[0];
    passed = true;
    tests = check[resultName];
    testKeys = Object.keys(tests);

    for (var j=0, jLen=testKeys.length; j<jLen && passed; j++) {
      passed = tests[testKeys[j]] === (values.indexOf(+testKeys[j]) != -1);
    }

    if (passed) return resultName;
  }
  return 'failed all tests...';
}

对象键:https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys

Array.prototype.indexOf: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf