Promise.any() – A Missing Use Case

promise.any-slim.js

Promise.any = function(arrayOfPromises) {
  // For each promise that resolves or rejects, 
  // make them all resolve.
  // Record which ones did resolve or reject
  var resolvingPromises = arrayOfPromises.map(function(promise) {
    return promise.then(function(result) {
      return {
        resolve: true,
        result: result
      };
    }, function(error) {
      return {
        resolve: false,
        result: error
      };
    });
  });

  return Promise.all(resolvingPromises).then(function(results) {
    // Count how many passed/failed
    var passed = [], failed = [], allFailed = true;
    results.forEach(function(result) {
      if(result.resolve) {
        allFailed = false;
      }
      passed.push(result.resolve ? result.result : null);
      failed.push(result.resolve ? null : result.result);
    });

    if(allFailed) {
      throw failed;
    } else {
      return passed;
    }
  });
};

promise.any.js

Promise.any = function(arrayOfPromises) {
  if(!arrayOfPromises || !(arrayOfPromises instanceof Array)) {
    throw new Error('Must pass Promise.any an array');
  }
    
  if(arrayOfPromises.length === 0) {
    return Promise.resolve([]);
  }
   
    
  // For each promise that resolves or rejects, 
  // make them all resolve.
  // Record which ones did resolve or reject
  var resolvingPromises = arrayOfPromises.map(function(promise) {
    return promise.then(function(result) {
      return {
        resolve: true,
        result: result
      };
    }, function(error) {
      return {
        resolve: false,
        result: error
      };
    });
  });

  return Promise.all(resolvingPromises).then(function(results) {
    // Count how many passed/failed
    var passed = [], failed = [], allFailed = true;
    results.forEach(function(result) {
      if(result.resolve) {
        allFailed = false;
      }
      passed.push(result.resolve ? result.result : null);
      failed.push(result.resolve ? null : result.result);
    });

    if(allFailed) {
      throw failed;
    } else {
      return passed;
    }
  });
};

solution.js

Promise.any([
    apiRequestPromise1,
    apiRequestPromise2,
    apiRequestPromise3
  ]).then(function(result) {
    // at least one of the API calls succeeded
    // navigate to new state  
  }, function() {
    // none of the API calls succeeded
    // don't navigate, show error  
  })

useful-return-value.js

var dataInPromise = apiCall('http://example.com');

useless-return-value.js

var totallyUseless = $.get('http://example.com', function(data) {
  // do something with the data   
});