原生态js方法实现全选复制功能

function selectCode(objid){

    var obj = document.getElementById(objid);

    obj.select();

}

function selectText(obj) {

    var text = obj;

    if (document.body.createTextRange) {

        var range = document.body.createTextRange();

        range.moveToElementText(text);

        range.select();

    } else if (window.getSelection) {

        var selection = window.getSelection();

        var range = document.createRange();

        range.selectNodeContents(text);

        selection.removeAllRanges();

        selection.addRange(range);

    } else {

        alert("none");

    }

}