確定是否存在請求的文檔，並確定它們是否存在，是否匹配請求的修訂版本號

Question

是否有比使用2 for循環和2 if語句更深的更好的方法？

的jsfiddle：

https://jsfiddle.net/bobbyrne01/bmnk9bLz/

代碼：

var documentsInDatabase = [{ 
    id: '1', 
    revision: '1' 
}, { 
    id: '2', 
    revision: '1' 
}, { 
    id: '3', 
    revision: '1' 
}]; 

// incorrect revision of document with id of 1, and non-existent document of id 4 
var requestedDocuments = [{ 
    id: '1', 
    revision: '2' 
}, { 
    id: '4', 
    revision: '1' 
}]; 

var result = { 
    ids_not_found: [], 
    revision_mismatches: [] 
}; 

// 4 nested blocks deep 
for (var i = 0; i < documentsInDatabase.length; i++) { 
    for (var j = 0; j < requestedDocuments.length; j++) { 
    if (documentsInDatabase[i].id === requestedDocuments[j].id) { 
     if (documentsInDatabase[i].revision !== requestedDocuments[j].revision) { 
     result.revision_mismatches.push(requestedDocuments[j].id); 
     } 

     requestedDocuments.splice(j, 1); 
     break; 
    } 
    } 
} 

for (var l = 0; l < requestedDocuments.length; l++) { 
    result.ids_not_found.push(requestedDocuments[l].id); 
} 

document.getElementById('container').innerHTML = JSON.stringify(result, null, 2); 

Answer 1

自卸documentsInDatabase成一個對象與id因爲這樣的關鍵：

var documentsInDatabaseObj = {}; 
for(var i = 0 ; i < documentsInDatabase.length ; i++){ 
    var id = documentsInDatabase[i].id; 
    documentsInDatabaseObj[id] = documentsInDatabase[i]; 
} 

現在遍歷requestedDocuments

for(var j = 0 ; j < requestedDocuments.length ; j++){ 
    var wantedId = requestedDocuments[j].id; 
    if(!documentsInDatabaseObj.hasOwnProperty(wantedId)){ 
     result.ids_not_found.push(wantedId); 
    } else if(documentsInDatabaseObj[wantedId].revision !== requestedDocuments[j].revision){ 
     result.revision_mismatches.push(wantedId); 
    } 
}