Function round

test/lib/testHelper.js:3243–3252

* Copied from src/util/number.ts

(x, precision, returnStr)

     * Copied from src/util/number.ts
     */
    function round(x, precision, returnStr) {
        if (precision == null) {
            precision = 10;
        }
        // Avoid range error
        precision = Math.min(Math.max(0, precision), ROUND_SUPPORTED_PRECISION_MAX);
        // PENDING: 1.005.toFixed(2) is '1.00' rather than '1.01'
        x = (+x).toFixed(precision);
        return (returnStr ? x : +x);
    }
    // Although chrome already enlarge this number to 100 for `toFixed`, but
    // we sill follow the spec for compatibility.
    var ROUND_SUPPORTED_PRECISION_MAX = 20;