Javascript Sync 2 or more array in a sort function

Zip 'em, sort 'em, unzip 'em. In very plain Javascript:

var zip = [];
for (var i = 0; i < Arr1.length; i++) {
    zip.push([Arr1[i], Arr2[i]]);
}

zip.sort(function (a, b) { return a[0] - b[0]; });

for (var i = 0; i < zip.length; i++) {
    Arr1[i] = zip[i][0];
    Arr2[i] = zip[i][1];
}

You could use the indices as a temporary array and sort it with the values of arr1. Then map the result to arr2.

var arr1 = [1, 1, 3, 2],
    arr2 = ['a', 'b', 'c', 'd'],
    indices = arr1.map(function (_, i) { return i; });

indices.sort(function (a, b) { return arr1[a] - arr1[b]; });
arr2 = indices.map(function (a) { return arr2[a]; });

console.log(arr2);

ES6

var arr1 = [1, 1, 3, 2],
    arr2 = ['a', 'b', 'c', 'd'];

arr2 = arr1
    .map((_, i) => i)
    .sort((a, b) => arr1[a] - arr1[b])
    .map(a => arr2[a]);

console.log(arr2);

if you use underscore, you can try this idea:

var sorted =_.map(new Array(4), function(i){
    return {
          a:Arra1[i],
          b:Arr2[i]
}
}).sort(function(item){return item.a; })

or js

var sorted = new Array(4).map(function(item,index){
return {
              a:Arra1[i],
              b:Arr2[i]
    }
};
sorted.sort(function(p,b){ return p.a-b.a;})

Arr1 = sorted.map(function(item){return item.a});
Arr2 = sorted.map(function(item){return item.b});

Assuming the two Arrays are Arr1, Arr2 and they have the same length:
1) Combine the two arrays:

var combined = [];
for (var i = 0; i < Arr1.length; i++) {
  combined.push({'arr1': Arr1[i], 'arr2': Arr2[i]});
}

2) Sort together:

combined.sort(function(a, b) {
  return a.arr1 < b.arr1; //ascending based on arr1
});

3) Separate:

for (var i = 0; i < combined.length; i++) {
  Arr1[i] = combined[i].arr1;
  Arr2[i] = combined[i].arr2;
}