js在开发大型组件库的时候经常会碰到很多的逻辑分支情况。

if(target === "font"){
  someFunction(){...}
}
else if(target === "code"){
  someFunction(){...}  
}
else if(target === "table"){
  someFunction(){...}
}
else if(target === "images"){
  someFunction(){...}
}
else if(target === "link"){
  someFunction(){...}  
}
else if(target === "file"){
  someFunction(){...}  
}

为了逻辑清晰当然也可以这样写：

switch(target){
    case : "font" :
           someFunction(){...} 
    break; 
    case : "code" :
           someFunction(){...} 
    break;
    case : "table" :
           someFunction(){...} 
    break; 
    case : "images" :
           someFunction(){...} 
    break; 
    case : "link" :
           someFunction(){...} 
    break;

　　case : "file" :
           someFunction(){...} 
    break;

}