检查JSON对象中的值

试试这个:

var id = 2,
    found = false;
for (var i=0; i<channels.length; i++) {
    if (channels[i].id == id) {
        found = true;
        break;
    }
}

或者更简洁,可能更快:

var id = 2; 
for (var found, i = channels.length; i && !(found = channels[--i].id === id);)
  ;