代码整洁之道-多个if else代码的优化

1、利用对象实现简单结构（单一）

let a=0,b=1;
let result = '';
if(a===1){
  if(b===1){
    result='a'
  }
  if(b===0){
    result='b'
  }
}

if(a===0){
  if(b===1){
    result='c'
  }
  if(b===0){
    result='d'
  }
}

优化为

let obj = {
  1: {
    0: 'a',
    1: 'b',
  },
  '-1': {
    0: 'c',
    1: 'd',
  },
}

let a = -1,b=0;
console.log(obj[a][b])

2、利用map实现多重结构（多值）

function functionA(){
  console.log("funA")
}
function functionB(){
  console.log("funA")
}
let maps = new Map([
  [{identity:'guest',status:1},functionA],
  [{identity:'guest',status:2},functionA],
  [{identity:'guest',status:3},functionA],
  [{identity:'guest',status:4},functionA],
  [{identity:'guest',status:5},functionB],
])

[...maps].forEach(item=>{
const [key,value] = item;
    console.log(item);
 	console.log(key,value);
 	console.log(key.status); // 1,2,3,4,5
});