问题
this might seem a silly question but I am a newbie in this topic. I am working on promises on node js. And I want to pass parameter to a promise function. However I could not figure it out.
someModule.someFunction.then(username, password,function(uid) {
/*stuff */
}
and the function is something like
var someFunction = new Promise(username, password, function(resolve, reject) {
/*stuff using username, password*/
if ( /* everything turned out fine */ ) {
resolve("Stuff worked!");
} else {
reject(Error("It broke"));
}
});
回答1:
Wrap your Promise inside a function or it will start to do its job right away. Plus, you can pass parameters to the function:
var someFunction = function(username, password) {
return new Promise(function(resolve, reject) {
/*stuff using username, password*/
if ( /* everything turned out fine */ ) {
resolve("Stuff worked!");
} else {
reject(Error("It broke"));
}
});
}
Then, use it:
someModule.someFunction(username, password).then(function(uid) {
/* stuff */
})
ES6:
const someFunction = (username, password) => {
return new Promise((resolve, reject) => {
/*stuff using username, password*/
if ( /* everything turned out fine */ ) {
resolve("Stuff worked!");
} else {
reject(Error("It broke"));
}
});
};
Use:
someModule.someFunction(username, password).then(uid => {
/* stuff */
});
回答2:
Another way(Must Try):
var promise1 = new Promise(function(resolve, reject) {
resolve('Success!');
});
var extraData = 'ImExtraData';
promise1.then(function(value) {
console.log(value, extraData);
// expected output: "Success!" "ImExtraData"
}, extraData);
回答3:
You can use .bind() to pass the param(this) to the function.
var someFunction =function(resolve, reject) {
/* get username, password*/
var username=this.username;
var password=this.password;
if ( /* everything turned out fine */ ) {
resolve("Stuff worked!");
} else {
reject(Error("It broke"));
}
}
var promise=new Promise(someFunction.bind({username:"your username",password:"your password"}));
来源:https://stackoverflow.com/questions/35318442/how-to-pass-parameter-to-a-promise-function