PHP 怎么字符串转换成json格式输出

这些代码整个是变量$html的值，我现在想把它转换为标准的json格式，最终把它变成一个json数组，便于输出调用！谁能帮我一下？
"data" : {
"price":"20.00",
"skuProps":[{"prop":"颜色",
"skuMap":{"白色L":{"canBookCount":1990},"白M":{"canBookCount":1989},"白色S":{"canBookCount":1988},"白色XL":{"canBookCount":1997},"黑色L":{"canBookCount":1996},"黑色":{"canBookCount":1997}}
}

相关了解……