# dig.mjs

    import round from 'lodash/round'
    import isnum from './isnum.mjs'
    import isp0int from './isp0int.mjs'
    import cdbl from './cdbl.mjs'

    /**
     * 數字取指定小數位的字串
     * 為字串故可自動補0
     * console.log(1.005.toFixed(2)) //1.00
     * console.log(dig(1.005, 2)) //1.01
     * 若輸入不是數字或字串時則回傳空字串
     *
     * Unit Test: {@link https://github.com/yuda-lyu/wsemi/blob/master/test/dig.test.mjs Github}
     * @memberOf wsemi
     * @param {Number|String} v 輸入數字或字串
     * @param {Integer} [idig=0] 輸入指定小數位整數，預設為0
     * @returns {String} 回傳取指定小數位的字串
     * @example
     *
     * console.log(dig(0.123456789, 3))
     * // => '0.123'
     *
     * console.log(dig(0.123456789, 4))
     * // => '0.1235'
     *
     */
    function dig(v, idig = 0) {

        //check
        if (!isnum(v)) {
            return ''
        }
        if (!isp0int(idig)) {
            return ''
        }

        v = cdbl(v)
        let r = round(v, idig).toFixed(idig) //IEEE754, toFixed回傳為string

        return r
    }

    export default dig