promise的基本使用
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <script> new Promise((resolve,reject)=>{ setTimeout(()=>{ resolve("abc") reject("sssss") },1000) }).then(data=>{ console.log(data); //第一次 return new Promise((resolve,reject)=>{ setTimeout(()=>{ resolve("sss") },1000) }).then(data=>{ console.log(data) //第二次 return new Promise((resolve,reject)=>{ setTimeout(() => { resolve("ccc") }, 1000); }).then(data=>{ console.log(data) },err=>{ console.log(err) }) })//简写err }) // }).catch(error=>{ // console.error(error); // }) </script> </body> </html>
promise的简写
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <script> new Promise((resolve,reject)=>{ setTimeout(()=>{ resolve("abc") reject("asdasd") },1000) }).then(data=>{ console.log(data); //第一次 return data+"a"//最简便 // return Promise.resolve(data+"a") 第二简便 }).then(data=>{ console.log(data) //第二次 return Promise.resolve("aad") }).then(data=>{ console.log(data) }).catch(err=>{ console.log(err) }) </script> </body> </html>
all的使用
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <script> Promise.all([ new Promise((resolve,reject)=>{ setTimeout(()=>{ resolve([{age:18,name:"wang"},'result1']) },1000) }), new Promise((resolve,reject)=>{ setTimeout(() => { resolve({age:17,name:"wangxingyu"},"result2") }, 1000); }) ]).then(results=>{ console.log(results); }) </script> </body> </html>