从javascript函数存储变量

Question

我正在尝试在运行函数后将字符串存储到变量中。当它运行时，它返回undefined。在底部我尝试添加return marginDirection;但它仍然返回未定义。我不确定我哪里出错了。我已经陷入困境。任何帮助，将不胜感激！感谢

var marginDirection = getMarginDirection();

            function getMarginDirection() {
                if (floatDirection == 'right') { 
                    marginDirection == 'left'; 
                    } 
                else if (floatDirection == 'left') { 
                    marginDirection == 'right'; 
                    } 
                else { 
                    marginDirection == ''; 
                    }
                };

Answer 1

function getMarginDirection()
{
    if (floatDirection == 'right')
        marginDirection = 'left'; 
    else if (floatDirection == 'left')
        marginDirection = 'right'; 
    else
        marginDirection = '';

    return marginDirection;
}

Return变量并指定=而不是==

的值