what is resolve

resolveis a parameter used in the Promise constructor, which is a function. When you create a new Promise object, you provide an executor function that takes two parameters: resolveand reject.

• resolve: This is a function that is called when the Promise fulfills successfully and can pass the result as an argument. Calling resolvecauses the Promise to transition from the "pending" state to the "fulfilled" state and sets the Promise's result value.
• reject: This is also a function that is called when the Promise fails, and can pass the reason for the error or failure as an argument. Calling rejectcauses the Promise to transition from the "pending" state to the "rejected" state and sets the Promise's rejection reason.

Here's a basic Promise example showing how to use resolveand reject:

const myPromise = new Promise((resolve, reject) => {
    
    
  const success = true; // 这里只是一个模拟条件

  if (success) {
    
    
    resolve('Promise was successful!'); // 成功时调用
  } else {
    
    
    reject('Promise failed.'); // 失败时调用
  }
});

myPromise.then(result => {
    
    
  console.log(result); // 输出 'Promise was successful!'
}).catch(error => {
    
    
  console.error(error); // 如果 Promise 失败，则输出错误
});

In this example:

• Called if successyes , passing the result to the subsequent method.trueresolve.then
• Called if successyes , passing the error to subsequent methods.falsereject.catch

When you use Promises to handle asynchronous operations, resolveand rejectallow you to control the fulfillment or failure of the Promise and pass the result or error to subsequent .thenor .catchhandlers in the chain.