函数作为参数进行传递

1 参数函数没有参数，按照正常流程执行

demo：

function fun1(someFun){

console.log('this is from fun1');

someFun();

}

function fun2(){

console.log('this is from fun2');

}

fun1(fun2)

 1 参数函数带参数，参数函数直接就执行了，在主函数中再次调用就会undifined

demo：

function fun1(someFun){

console.log('this is from fun1');

someFun();

}

function fun2(num){

console.log('this is from fun2');

console.log(num);

}

fun1(fun2(100))

 解决办法，直接把参数和函数名作为两个参数进行传递：

demo:

function fun1(someFun,somedata){

console.log('this is from fun1');

someFun(somedata);

}

function fun2(num){

console.log('this is from fun2');

console.log(num);

}
fun1(fun2,1000)