javascript痛点之四回调函数

function study(){
   console.log("studying...");
}

function play(){
   console.log("playing...");
}

function sleep(){
  console.log("sleeping....");
}

function doWhat(funName){
   console("我正在");
   funName();
}
doWhat(study);//我正在studying...
doWhat(play);//我正在playing...
doWhat(sleep);//我正在sleeping...

function study(name){
   console.log(name+" "+"studying...");
}

function play(name){
   console.log(name+" "+"playing...");
}

function sleep(name){
  console.log(name+" "+"sleeping....");
}

function doWhat(funName,name){
   funName(name);
}
doWhat(study,‘xiaoming‘);//xiaoming studying...
doWhat(play,‘xiaodong‘);//xiaodong playing...

function add(a,b){
  console.log(a+b);
}

function reduce(a,b){
  console.log(a-b);
}

function calc(funName,fn1,fn2){
   funName(fn1,fn2);
}

calc(add,5,4);//9
calc(reduce,5,4);//1