//字符串转布尔
        var a = 'true'
        //console.log(a, typeof a)
        var a1 = Boolean(a)
        //console.log(a1, typeof a1)

        //布尔转字符串
        var b = true
        //console.log(b, typeof b)
        //var b1 = b.toString()
        var b1 = String(b)
        //console.log(b1, typeof b1)

        //转为数字
        var c = '2.23, 2.3'
        //parseFloat():   parseFloat()把字符串转换成浮点数,parseFloat()和parseInt非常相似，
        //不同之处在于parseFloat会解析第一个. 遇到第二个.或者非数字结束如果解析的内容里只有整数，解析成整数
        console.log(c, typeof c)
        //var c1 = parseInt(c)
        //var c1 = parseFloat(c)
        var c1 = Number(c)
        console.log(c1, typeof c1)