javascript痛點之四回呼函數

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先來看看什麼是回呼函數(callback)

回呼函數就是調用函數的時候將另一個函數的名稱當作參數傳遞進去,並且在函數體中進行調用。

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...

帶參數的

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...

也可以帶很多參數,我們寫一個計算的例子

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

這就是回呼函數(callback);

希望對你理解回呼函數有協助（完

javascript痛點之四回呼函數