If you are not interested in support for old browsers, the best way to browse an array of json is:
var dotArrayJSON = [
                    {"label": 1}, 
                    {"label": 2}, 
                    {"label": 3}, 
                    {"label": 4}
                   ];
dotArrayJSON.forEach(loopThrough);
function loopThrough(JSON) {
    console.log(JSON.label)
}
Otherwise with a simple for:
for(var i = 0; i < dotArrayJSON.length; i++) {
    var obj = dotArrayJSON[i];
    console.log(obj.label);
}