1If you create an object of cooldowns you can get how much time they would have left by subtracting the date from the cooldown.
2Like so:
3//Start of code or something
4var cooldowns = {}
5var minute = 60000;
6var hour = minute * 24;
7//Set cooldown
8cooldowns[message.author.id] = Date.now() + hour * 24; //Set a 24 hour cooldown
9//At command check
10if(cooldowns[message.author.id]){
11if(cooldowns[message.author.id] > Date.now()) delete cooldowns[message.author.id];
12else console.log("user still has " + Math.round((cooldowns[message.author.id] - Date.now)/minute) + " minutes left")
13}
14