javascript - 在javascript中过滤对象数组

Question

我真的是 JS 的新手，我现在被困在一个任务上，希望有人能指导我完成它。

我有一个对象数组，如下所示:

var labels = [
            // labels for pag 1
            {pageID:1, labels: [
                {labelID:0, content:[{lang:'eng', text:'Txt1 Eng'}, {lang:'de', text:'Txt1 De:'}]},
                {labelID:1, content:[{lang:'eng', text:'Txt 2 Eng:'}, {lang:'de', text:'Txt2 De:'}]},
                {labelID:2, content:[{lang:'eng', text:'Txt 3 Eng:'},{lang:'de', text:'Txt 3 De:'}]}
            ]},

            // labels for pag 2
            {pageID:2, labels: [
                {labelID:0, content:[{lang:'eng', text:'Txt1 Eng'}, {lang:'de', text:'Txt1 De:'}]},
                {labelID:1, content:[{lang:'eng', text:'Txt 2 Eng:'}, {lang:'de', text:'Txt2 De:'}]},
                {labelID:2, content:[{lang:'eng', text:'Txt 3 Eng:'},{lang:'de', text:'Txt 3 De:'}]}
            ]}
    ]

我想做的是编写一个函数，为特定页面和特定语言返回一组标签(对象)。通过调用指定 pageID 1 和 lang eng 的函数，我基本上是在尝试构建这样一个数组:

var desideredArray = [
    {labelID:0, text:'Txt1 Eng'}, 
    {labelID:1, text:'Txt1 Eng'}, 
    {labelID:2, text:'Txt2 Eng'}
] 

现在，我正在尝试编写函数来检索/构建新数组:

this.getLabelsForPageAndLang = function (numPage, lang) {
            // this part filters the main object and selects the object with pageID == numPage
        var result = labels.filter(function( obj ) {
            return obj.pageID == numPage;
        });

        var tempResult = result[0].labels;
        var desiredResults = [];  // here I want to store the new objects
        for (var i=0; i<tempResult.length; i++) {
            var simpleLabelObject = {};
            simpleLabelObject.labelID = tempResult[i].labelID;
            // simpleLabelObject.text = ?????

            results[i] = simpleLabelObject;
        }

        console.log (results);

    };

...但是如何在内容属性中访问正确的值(对应于所选语言的值)？

Answer 1

您可以使用与保留匹配页面相同的技术:filter 方法。

this.getLabelsForPageAndLang = function (numPage, lang) {
        // this part filters the main object and selects the object with pageID == numPage
    var result = labels.filter(function( obj ) {
        return obj.pageID == numPage;
    });
    var contentFilter = function(obj){ return obj.lang === lang};

    var tempResult = result[0].labels;
    var desiredResults = [];  // here I want to store the new objects
    for (var i=0; i<tempResult.length; i++) {
        var simpleLabelObject = {};
        simpleLabelObject.labelID = tempResult[i].labelID;
        var matching = tempResult[i].content.filter(contentFilter);
        simpleLabelObject.text = matching[0].text;

        desiredResults[i] = simpleLabelObject;
    }

    console.log (desiredResults);

};

我没有进行绑定(bind)检查，因为在您的代码中您假定始终存在匹配元素，但这样做可能是明智的。

如果你想避免每次调用函数时创建两个闭包，你可以为此创建一个对象原型(prototype):

var Filter = function(numPage, lang) {
    this.numPage = numPage;
    this.lang = lang;
};

Filter.prototype.filterPage = function(obj) {
    return obj.pageID === this.numPage;
}

Filter.prototype.filterLang = function(obj) {
    return obj.lang === this.lang;
}

Filter.prototype.filterLabels = function(labels) {
    var result = labels.filter(this.filterPage, this);

    var tempResult = result[0].labels;
    var desiredResults = [];  // here I want to store the new objects
    for (var i=0; i<tempResult.length; i++) {
        var simpleLabelObject = {};
        simpleLabelObject.labelID = tempResult[i].labelID;
        var matching = tempResult[i].content.filter(this.filterLang, this);
        simpleLabelObject.text = matching[0].text;

        desiredResults[i] = simpleLabelObject;
    }

    return desiredResults;
}

console.log(new Filter(1, "eng").filterLabels(labels));