Is it possible to create the the data1 array without using nested for loops?
// My starting Normalized data
var fields = ["name","age"];
var data2 = [["John",20],["Tom",25]];
// What I want the result to look like Denormalized
var data1 = [{"name":"John", "age":20},{"name":"Tom", "age":25}];
// My solution
var data1 = [];
for(var i = 0; i < data2.length; i++){
var temp = {};
for(var y = 0; y < fields.length; y++){
temp[fields[y]] = data2[i][y];
}
data1.push(temp);
}
var fields = ["name","age"];
var data2 = [["John",20],["Tom",25]];
var data1 = data2.map(function(arr){
var obj = {};
arr.forEach(function(val, ind){ obj[fields[ind]] = val; });
return obj;
});
but it is basically nest loops.
Or you could start getting acquainted with Javascript tools like the underscore/lodash libraries that offer a lot of utilities functions for cases like this.
For example, using _.zipObject() offered by lodash:
fields = ["name", "age"];
data2 = [["John", 20],["Tom", 25]];
res = [];
data2.forEach(function(arr) {
res.push(_.zipObject(fields, arr));
});
In essence as @epascarello mentioned, you are still doing a double loop. It's just more elegant (subject always to coding taste) and more compact.
No loops...
var data1 = [];
data1.push(eval('({"' + fields[0] + '":"' + data2[0][0] +
'","' + fields[1] + '":' + data2[0][1] + '})'));
data1.push(eval('({"' + fields[0] + '":"' + data2[1][0] +
'","' + fields[1] + '":' + data2[1][1] + '})'));
Guess it depends on your definition of efficient.
Another implementation using native map and reduce (which will be nested loops - but figured I'd throw it in as another option):
var data1 = data2.map(function(currentArray, index){
return currentArray.reduce(function(objToReturn, currentValue, index){
objToReturn[fields[index]] = currentValue;
return objToReturn;
},{});
});
I finally thought of an efficient way that doesn't use nest for loops! :)
var fields = ["name","age"];
var data2 = [["John",20],["Tom",25]];
var body = "";
for(var i = 0; i < fields.length; i++){
body = body.concat("this."+fields[i] +"=args["+i+"]; ");
}
var model = new Function("args",body);
var data1 = [];
for(var i = 0; i < data2.length; i++){
var x = new model(data2[i]);
data1.push(x);
}
new Function is not "cheap".