Question

我有下面的JSON，它控制应用程序中页面的流向。要手动在屏幕之间导航，我使用页面的索引。如果要链接到Page 1，我将使用索引“ 0”。我希望能够使用id进行导航。因此，我可以使用S010_010进行导航。不幸的是，该应用程序的导航功能被多个元素使用，并且无法完全更改，因此我正在寻找一种可以获取ID并从flows返回索引的方法。

var flows = {
  "default": [{
      theme: "theme1",
      events: "touchstart",
      easingSlideIn: "transition.fadeIn",
      easingSlideOut: "transition.fadeOut",
      easingRef: "transition.perspectiveRightIn",
      easingPop: "transition.flipYIn"
    },
    {
      id: "S010_010", //0
      description: "",
      chapter: "01",
      ref: ""
    },
    {
      id: "S020_010", //1
      description: "",
      chapter: "01",
      ref: ""
    },
    {
      id: "S030_010", //2
      description: "",
      chapter: "01",
      ref: ""
    },
  ]
};

这是我当前如何使用索引检索id的示例：

this.options.flow[screen +1].id

Answer 1

没有特定的方法，但是您可以创建自己的倒排索引

var invertedIndex = {};
flows.default.forEach((elem, index) => {
   if(elem.id != null) {
      invertedIndex[elem.id] = index - 1;
   }
})
//then you can use the id for the lookup as
invertedIndex['S030_010']

Answer 2

如果id与方法的匹配，则可以使用for-in进行迭代并返回索引。还建议使用for-of，但是最终您会放弃使用类似for(const [index, value] of flows.default.entries())的东西来获取索引，因此使用for-in

let flows = {
  "default": [{
      theme: "theme1",
      events: "touchstart",
      easingSlideIn: "transition.fadeIn",
      easingSlideOut: "transition.fadeOut",
      easingRef: "transition.perspectiveRightIn",
      easingPop: "transition.flipYIn"
    },
    {
      id: "S010_010", //0
      description: "",
      chapter: "01",
      ref: ""
    },
    {
      id: "S020_010", //1
      description: "",
      chapter: "01",
      ref: ""
    },
    {
      id: "S030_010", //2
      description: "",
      chapter: "01",
      ref: ""
    },
  ]
};

let getFlowByID = (id) => {
for(let eachFlowIndex in flows.default){
	if(flows.default[eachFlowIndex].id == id){
		return eachFlowIndex;
	}
 }
}

console.log(getFlowByID("S030_010")); // gets S030_010 index

Answer 3

我们使用for in循环来遍历对象数组，如果找到id，则返回索引。

ES5解决方案

var flows =
{
    "default":
    [
        {
            theme: "theme1",
            events: "touchstart",
            easingSlideIn: "transition.fadeIn",
            easingSlideOut: "transition.fadeOut",
            easingRef: "transition.perspectiveRightIn",
            easingPop: "transition.flipYIn"
        },
        {
            id: "S010_010", //0
            description: "",
            chapter: "01",
            ref: ""
        },
        {
            id: "S020_010", //1
            description: "",
            chapter: "01",
            ref: ""
        },
        {
            id: "S030_010", //2
            description: "",
            chapter: "01",
            ref: ""
        }
    ]
};

function getIndex(id)
{
    var i = 0,
        objs = flows.default;

    for (i in objs)
        if (objs[i].id == id)
            return +i - 1
}

console.log(getIndex('S010_010')); //0

ES6解决方案

我们使用 Array.find 函数遍历数组，如果找到ID，则保存索引，然后返回索引。如果找不到，它将返回-1。但是不幸的是，该解决方案并不比我的ES5解决方案短。

var flows =
{
    "default":
    [
        {
            theme: "theme1",
            events: "touchstart",
            easingSlideIn: "transition.fadeIn",
            easingSlideOut: "transition.fadeOut",
            easingRef: "transition.perspectiveRightIn",
            easingPop: "transition.flipYIn"
        },
        {
            id: "S010_010", //0
            description: "",
            chapter: "01",
            ref: ""
        },
        {
            id: "S020_010", //1
            description: "",
            chapter: "01",
            ref: ""
        },
        {
            id: "S030_010", //2
            description: "",
            chapter: "01",
            ref: ""
        }
    ]
};

let getIndex = (id) => {

    let ret = -1;
    flows.default.find((elem, index) => {
        if(elem.id == id)
            ret = index - 1
    });
    return ret
};


console.log(getIndex('S010_010')); //0

使用Javascript根据子键值查找JSON索引

3 个答案: