js arrotondare numeri

1 // value is the value to round
2 // places if positive the number of decimal places to round to
3 // places if negative the number of digits to round to
4 function roundTo(value, places){
5     var power = Math.pow(10, places);
6     return Math.round(value * power) / power;
7 }
8 var myNum = 10000/3;    // 3333.3333333333335
9 roundTo(myNum, 2);  // 3333.33
10 roundTo(myNum, 0);  // 3333
11 roundTo(myNum, -2); // 3300
12

1 function ceilTo(value, places){
2     var power = Math.pow(10, places);
3     return Math.ceil(value * power) / power;
4 }
5 function floorTo(value, places){
6     var power = Math.pow(10, places);
7     return Math.floor(value * power) / power;
8 }
9

1var a = Math.round(2.3);       // a is now 2  
2var b = Math.round(2.7);       // b is now 3
3var c = Math.round(2.5);       // c is now 3
4
5var a = Math.ceil(2.3);        // a is now 3
6var b = Math.ceil(2.7);        // b is now 3
7
8Input  : Math.floor(5.78)
9Output : 5
10
11Input  : Math.floor(1.5)
12Output : 1