setTimeOut，setInterval的第三个参数

function sum(x, y) {
    console.log(x+y) 
}
setTimeout(sum, 1000, 1, 3);

 

此处的 1和3  理解为传递的是第一个参数 sum的参数

 

多个参数需要传递数组格式

demo1

const promise = new Promise((resolve, reject) => {
    setTimeout(resolve,1000,'参数1','参数2');
})

promise.then((value1,value2) => {
    console.log('value1:' + value1)     //value1:参数1
    console.log('value2:' + value2)     //value2:undefined
}).catch((value) => {
    console.log(value)
})

demo2

const promise = new Promise((resolve, reject) => {
    setTimeout(resolve,1000,['参数1','参数2']);
})

promise.then(([value1,value2]) => {
    console.log('value1:' + value1)     //value1:参数1
    console.log('value2:' + value2)     //value2:参数2
}).catch((value) => {
    console.log(value)
})