copy whole html table to clipboard javascript

I have write javascript to select the table but I want to now automaticaly copy it after the click of the button.Please help me.My javascript is like this.

function selectElementContents(el) {
            var body = document.body, range, sel;
            if (document.createRange && window.getSelection) {
                range = document.createRange();
                sel = window.getSelection();
                sel.removeAllRanges();
                try {
                    range.selectNodeContents(el);
                    sel.addRange(range);
                    document.execCommand('Copy');
                } catch (e) {
                    range.selectNode(el);
                    sel.addRange(range);
                    document.execCommand('Copy');
                }
            } else if (body.createTextRange) {
                range = body.createTextRange();
                range.moveToElementText(el);
                range.select();
                range.execCommand('Copy');

            }
        }