Function getPrecision

src/util/number.ts:265–290

(val: string | number)

 * e.g. `getPrecisionSafe(100)` return `0`.
 */
export function getPrecision(val: string | number): number {
    val = +val;
    if (isNaN(val)) {
        return 0;
    }

    // It is much faster than methods converting number to string as follows
    //      let tmp = val.toString();
    //      return tmp.length - 1 - tmp.indexOf('.');
    // especially when precision is low
    // Notice:
    // (1) If the loop count is over about 20, it is slower than `getPrecisionSafe`.
    //     (see https://jsbench.me/2vkpcekkvw/1)
    // (2) If the val is less than for example 1e-15, the result may be incorrect.
    //     (see test/ut/spec/util/number.test.ts `getPrecision_equal_random`)
    if (val > 1e-14) {
        let e = 1;
        for (let i = 0; i < 15; i++, e *= 10) {
            if (mathRound(val * e) / e === val) {
                return i;
            }
        }
    }

    return getPrecisionSafe(val);
}

/**
 * Get precision with slow but safe method