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| function myPromise(fn) {
var state = 'pending',
value = null,
callbacks = [];
this.then = function(onFulfilled = null){
return new Promise((resolve)=>{
handle({
onFulfilled,
resolve
})
})
}
function handle(callback) {
if(state == 'pending') {
callbacks.push(callback)
return
}
if(!callback.onFulfilled) {
callback.resolve(value)
return
}
var ret = callback.onFulfilled(value)
callback.resolve(ret)
}
function resolve(newValue) {
if(newValue && typeof newValue == 'function' || typeof newValue == 'object'){
var then = newValue.then
if(newValue.then){
then.call(newValue, resolve)
}
}
state = 'fulfilled';
value = newValue
setTimeout(()=>{
callbacks.map((cb)=>{
handle(cb)
})
},0)
}
fn(resolve)
}
|
