Promi捕获错误
1.捕获执⾏器异常
constMyPromi=require('./myPromi')
letpro=newMyPromi((resolve,reject)=>{
thrownewError('executorerror')
resolve('hello')
})
(value=>{
(value)
},reason=>{
(e)
})
constPENDING='pending'//等待
constFULFILLED='fulfilled'//成功
constREJECTED='rejected'//失败
classMyPromi{
constructor(executor){
//捕获执⾏器错误
try{
executor(e,)
}catch(e){
(e)
}
}
status=PENDING
value=undefined
reason=undefined
successCallback=[]
failCallback=[]
resolve=value=>{
if(!==PENDING)return
//将状态修改为成功
=FULFILLED
//保存成功之后的值
=value
//sCallback&&sCallback()
while(){
()()
}
}
reject=reason=>{
if(!==PENDING)return
=REJECTED
=reason
//llback&&llback()
while(){
()()
}
}
then(successCallback,failCallback){
letpromi2=newMyPromi((resolve,reject)=>{
if(===FULFILLED){
tTimeout(()=>{
letx=successCallback()
//resolve(x)
resolvePromi(promi2,x,resolve,reject)
},0)
}elif(===REJECTED){
failCallback()
}el{
//等待
//讲成功回调和失败回调进⾏存储
(successCallback)
(failCallback)
}
})
})
returnpromi2
}
}
functionresolvePromi(promi2,x,resolve,reject){
if(promi2===x){
returnreject(newTypeError('Chainingcycledetectedforpromi#
}
if(xinstanceofMyPromi){
//(value=>resolve(value),reason=>reject(reason))
(resolve,reject)
}el{
resolve(x)
}
}
s=MyPromi
函数抛出异常
letpro=newMyPromi((resolve,reject)=>{
//thrownewError('executorerror')
resolve('hello')
})
(value=>{
(value)
thrownewError('thenerror')
},reason=>{
(e)
}).then(value=>{
(value)
},reason=>{
(e)
})
constPENDING='pending'//等待
constFULFILLED='fulfilled'//成功
constREJECTED='rejected'//失败
classMyPromi{
constructor(executor){
//捕获执⾏器错误
try{
executor(e,)
}catch(e){
(e)
}
}
status=PENDING
value=undefined
reason=undefined
successCallback=[]
failCallback=[]
resolve=value=>{
if(!==PENDING)return
//将状态修改为成功
=FULFILLED
//保存成功之后的值
=value
//sCallback&&sCallback()
while(){
()()
}
}
reject=reason=>{
if(!==PENDING)return
=REJECTED
=reason
=reason
//llback&&llback()
while(){
()()
}
}
then(successCallback,failCallback){
letpromi2=newMyPromi((resolve,reject)=>{
if(===FULFILLED){
tTimeout(()=>{
try{
letx=successCallback()
//判断x的值是普通值还是promi对象
//如果是普通值，直接调⽤resolve
//如果是promi对象，查看promi对象返回的结果
//再根据promi对象返回的结果，决定调⽤resolve还是reject
resolvePromi(promi2,x,resolve,reject)
}catch(e){
reject(e)
}
},0)
}elif(===REJECTED){
failCallback()
}el{
//等待
//讲成功回调和失败回调进⾏存储
(successCallback)
(failCallback)
}
})
returnpromi2
}
}
functionresolvePromi(promi2,x,resolve,reject){
if(promi2===x){
returnreject(newTypeError('Chainingcycledetectedforpromi#
}
if(xinstanceofMyPromi){
//(value=>resolve(value),reason=>reject(reason))
(resolve,reject)
}el{
resolve(x)
}
}
s=MyPromi
3.异步情况的处理
constPENDING='pending'//等待
constFULFILLED='fulfilled'//成功
constREJECTED='rejected'//失败
classMyPromi{
constructor(executor){
//捕获执⾏器错误
try{
executor(e,)
}catch(e){
(e)
}
}
status=PENDING
value=undefined
reason=undefined
successCallback=[]
failCallback=[]
resolve=value=>{
if(!==PENDING)return
//将状态修改为成功
=FULFILLED
=FULFILLED
//保存成功之后的值
=value
//sCallback&&sCallback()
while(){
()()
}
}
reject=reason=>{
if(!==PENDING)return
=REJECTED
=reason
//llback&&llback()
while(){
()()
}
}
then(successCallback,failCallback){
letpromi2=newMyPromi((resolve,reject)=>{
if(===FULFILLED){
tTimeout(()=>{
try{
letx=successCallback()
//判断x的值是普通值还是promi对象
//如果是普通值，直接调⽤resolve
//如果是promi对象，查看promi对象返回的结果
//再根据promi对象返回的结果，决定调⽤resolve还是reject
resolvePromi(promi2,x,resolve,reject)
}catch(e){
reject(e)
}
},0)
}elif(===REJECTED){
tTimeout(()=>{
try{
letx=failCallback()
//判断x的值是普通值还是promi对象
//如果是普通值，直接调⽤resolve
//如果是promi对象，查看promi对象返回的结果
//再根据promi对象返回的结果，决定调⽤resolve还是reject
resolvePromi(promi2,x,resolve,reject)
}catch(e){
reject(e)
}
},0)
}el{
//等待
//讲成功回调和失败回调进⾏存储
(()=>{
tTimeout(()=>{
try{
letx=successCallback()
//判断x的值是普通值还是promi对象
//如果是普通值，直接调⽤resolve
//如果是promi对象，查看promi对象返回的结果
//再根据promi对象返回的结果，决定调⽤resolve还是reject
resolvePromi(promi2,x,resolve,reject)
}catch(e){
reject(e)
}
},0)
})
(()=>{
tTimeout(()=>{
try{
letx=failCallback()
//判断x的值是普通值还是promi对象
//如果是普通值，直接调⽤resolve
//如果是promi对象，查看promi对象返回的结果
//再根据promi对象返回的结果，决定调⽤resolve还是reject
resolvePromi(promi2,x,resolve,reject)
}catch(e){
reject(e)
}
}
},0)
})
}
})
returnpromi2
}
}
functionresolvePromi(promi2,x,resolve,reject){
if(promi2===x){
returnreject(newTypeError('Chainingcycledetectedforpromi#
}
if(xinstanceofMyPromi){
//(value=>resolve(value),reason=>reject(reason))
(resolve,reject)
}el{
resolve(x)
}
}
s=MyPromi
letpro=newMyPromi((resolve,reject)=>{
//thrownewError('executorerror')
//resolve('hello')
//reject('失败')
tTimeout(()=>{
resolve('成功。。。')
},2000)
})
(value=>{
(value+'1')
//thrownewError('thenerror')
return'aaa'
},reason=>{
(reason+'2')
return10000
}).then(value=>{
(value+'3')
})
本文发布于:2022-12-29 05:31:24，感谢您对本站的认可！
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