The identifier "resolve" in the catch block has not been defined

Question

The identifier "resolve" in the catch block has not been defined

Why is it not possible to call resolve in the catch block?

I wanted to catch a failed request and attempt it again in the catch block, but I am encountering an issue where resolve is not defined. I am confused since I am inside of the promise, so why is it not allowing me to call resolve?

module.exports.makeRequest = function(ID, requestAttempts) {

return new Promise(function(resolve, reject) {
    request.get(url, {json:true}, function(err, res) {
        if(err || res.body.error_code)
            reject(err || res.body)
        else
            resolve(res.body)
    })
})
.catch(function(error) {
    if (requestAttempts <= 0) {
        reject(error);
    }
    console.log("Error:", error, `\n Try to repeat the request (attempts left: ${requestAttempts})`); 
    resolve(makeRequest(ID, requestAttempts - 1));
});

}

javascript promise

Answer 1

Answer №1

The Promise constructor requires a function with resolve and reject, while .then does not. To resolve from a .then or a .catch, simply return the value. To reject from a .then or a .catch, just throw an error.

If you're looking for a similar structure, consider the following example. Remember, the logic may need adjustment to suit your needs:

function makeRequest(ID, requestAttempts) {
   return Promise((resolve, reject) => {
       request.get(url, {json:true}, function(err, res) {
          if(err || res.body.error_code)
              reject(err || res.body)
          else
              resolve(res.body)
       })
    })
}

 makeRequest().catch(function (error) {
     if (requestAttempts <= 0) throw error;
        console.log("Error :",error, `\n Try to repeat the request (attempts 
        left: ${requestAttempts} )`); 
    return makeRequest(ID, requestAttempts - 1));
 });

Answer 2

The Promise constructor requires a function with resolve and reject, while .then does not. To resolve from a .then or a .catch, simply return the value. To reject from a .then or a .catch, just throw an error.

If you're looking for a similar structure, consider the following example. Remember, the logic may need adjustment to suit your needs:

function makeRequest(ID, requestAttempts) {
   return Promise((resolve, reject) => {
       request.get(url, {json:true}, function(err, res) {
          if(err || res.body.error_code)
              reject(err || res.body)
          else
              resolve(res.body)
       })
    })
}

 makeRequest().catch(function (error) {
     if (requestAttempts <= 0) throw error;
        console.log("Error :",error, `\n Try to repeat the request (attempts 
        left: ${requestAttempts} )`); 
    return makeRequest(ID, requestAttempts - 1));
 });

Answer 3

Answer №2

Your implementation of the Promise constructor seems to have some errors. The resolve function is not properly placed within the .catch function's callback, leading to scope issues. Additionally, the makeRequest function is not accessible in the local scope, making it impossible to call itself.

I recommend moving the "retry" logic outside of the main function responsible for processing the AJAX request.

function makeOneRequest(ID) {
    return new Promise((resolve, reject) => {
         request.get(url, {json: true}, (err, res) => {
             if (err || res.body.error_code) {
                 reject(err || res.body);
             } else {
                 resolve(res.body);
             }
         });
    });
}

function makeRequest(ID, count) {
    if (count <= 0) {
        return Promise.reject();
    } else {
        return makeOneRequest(ID).catch(() => makeRequest(ID, count - 1);
    }
}

module.exports.makeRequest = makeRequest;

Answer 4

Your implementation of the Promise constructor seems to have some errors. The resolve function is not properly placed within the .catch function's callback, leading to scope issues. Additionally, the makeRequest function is not accessible in the local scope, making it impossible to call itself.

I recommend moving the "retry" logic outside of the main function responsible for processing the AJAX request.

function makeOneRequest(ID) {
    return new Promise((resolve, reject) => {
         request.get(url, {json: true}, (err, res) => {
             if (err || res.body.error_code) {
                 reject(err || res.body);
             } else {
                 resolve(res.body);
             }
         });
    });
}

function makeRequest(ID, count) {
    if (count <= 0) {
        return Promise.reject();
    } else {
        return makeOneRequest(ID).catch(() => makeRequest(ID, count - 1);
    }
}

module.exports.makeRequest = makeRequest;

The identifier "resolve" in the catch block has not been defined

Answer №1

Answer №2

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