# calculate % change in javascript

Note that if one of your values is 0 you will get either -100% or Infinity%. This solves that problem:

```
function percIncrease(a, b) {
let percent;
if(b !== 0) {
if(a !== 0) {
percent = (b - a) / a * 100;
} else {
percent = b * 100;
}
} else {
percent = - a * 100;
}
return Math.floor(percent);
}
```

Its simple maths:

```
var res=(current-june)/current*100.0;
```