Function floatFixed

floatFixed(num, size?): string
EN: Keep the specified number of decimal places for floating-point numbers.

ZH: 浮点数保留指定位。

Usage:
```
const ret1 = floatFixed(0.2);
const ret2 = floatFixed(0.2, 2);
console.log(ret1);
console.log(ret2);
```
Output:
```
0
0.20
```
Parameters
- num: string
- size: number = 0
Returns string
- Defined in util.ts:392