.
的情况。const extname = (filename) => {
let arr=filename.split(".");
let len=arr.length;
let extname=''
if(len>1){
extname = arr[len-1];
extname =arr[len-2]==''?'': `.${extname}`;
return extname
}
return extname
}
pause 函数可以让一个函数暂停运行一段时间(ms)以后继续运行。例如
async function run () {
console.log('Hello')
await pause(1000) // 续一秒
console.log('World') // 一秒以后继续运行
}
//利用系统时间计时与进入的时间差
const pause = async (time) => {
let nowTime=(new Date()).getTime();
while(true){
if( (new Date()).getTime()-nowTime>=time){
return
}
}
}
//promise异步模型
const pause = async (time) => {
return new Promise((resolve,reject)=>{
setTimeout(resolve,time);
})
}
从某数据库接口得到如下值:
{
rows: [
["Lisa", 16, "Female", "2000-12-01"],
["Bob", 22, "Male", "1996-01-21"]
],
metaData: [
{ name: "name", note: '' },
{ name: "age", note: '' },
{ name: "gender", note: '' },
{ name: "birthday", note: '' }
]
}
rows 是数据,metaData 是对数据的说明。现写一个函数 parseData,将上面的对象转化为期望的数组:
[
{ name: "Lisa", age: 16, gender: "Female", birthday: "2000-12-01" },
{ name: "Bob", age: 22, gender: "Male", birthday: "1996-01-21" },
]
//转换的方法
const parseData = (data) => {
var rows=data.rows
var len=rows.length
var meta=data.metaData
var len2=meta.length
var arr=[]
for(let i=0;i<len;i++){
var temp={}
for(let j=0;j<len2;j++){
temp[meta[j].name]=rows[i][j]
}
arr.push(temp)
}
return arr
}