# dtpick.mjs

    import each from 'lodash/each'
    import get from 'lodash/get'
    import isobj from './isobj.mjs'
    import isearr from './isearr.mjs'
    import haskey from './haskey.mjs'

    /**
     * 由dt物件提取指定keys欄位出來成為新物件，僅保留有keys的欄位，若不存在欄位就不提取
     *
     * Unit Test: {@link https://github.com/yuda-lyu/wsemi/blob/master/test/dtpick.test.mjs Github}
     * @memberOf wsemi
     * @param {Object} dt 輸入資料物件
     * @param {Array} keys 輸入要提取欄位集合的字串陣列
     * @returns {Object} 回傳處理後物件
     * @example
     *
     * console.log(dtpick({ a: 'a123', b: 234, c: '345' }, ['a', 'b']))
     * // => { a: 'a123', b: 234 }
     *
     * console.log(dtpick({ a: 'a123', b: 234, c: '345' }, ['a', 'b', 'x']))
     * // => { a: 'a123', b: 234 }
     *
     */
    function dtpick(dt, keys) {

        //check
        if (!isobj(dt)) {
            return {}
        }
        if (!isearr(keys)) {
            return {}
        }

        let r = {}
        each(keys, function(key) {
            if (haskey(dt, key)) {
                r[key] = get(dt, key)
            }
        })

        return r
    }

    export default dtpick