function selectText() {
    if (document.selection) {
        var range = document.body.createTextRange();
        range.moveToElementText(document.getElementById('selectable'));
        range.select();
    } else if (window.getSelection) {
        var range = document.createRange();
        range.selectNode(document.getElementById('selectable'));
        window.getSelection().addRange(range);
    }
}

试试这个方法能在小程序里选中文本吗