问Javascript最初跳过嵌套函数，然后又返回到它？
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Stack Overflow用户

提问于 2019-02-26 15:28:12

回答 1查看 68关注 0票数 0

我在我的代码中遇到了一些奇怪的行为，我不太理解。我调用了一个函数，在该函数内部有另一个(匿名)回调函数，它跳过并转到包含函数的末尾，运行这些行，然后返回回调函数并运行这些行……有没有人知道我做错了什么？它这样做是因为"relatedQuery“方法还没有完成，所以它在运行包含函数的其余行之前没有命中回调函数吗？这是我能想到的唯一一件事，但我对JS也不是很熟练。我已经添加了一些console.log语句，它们将告诉您命中行的顺序。

//Call the mgmtPopupContent function
mgmtTractPopupBox.setContent(mgmtPopupContent);

function mgmtPopupContent(feature) {
    for (var attrb in feature.attributes) {
        if (attrb == "HabitatManagement.DBO.MgmtTracts.OBJECTID") {
            var OID = feature.attributes[attrb];
        }
    }
    var relatedQuery = new RelationshipQuery();
    relatedQuery.outFields = ["*"];
    relatedQuery.relationshipId = 0;
    relatedQuery.objectIds = [OID];
    //Get data year that the map view is set to and set the definition expression on the table
    viewYear = dom.byId("data-year").value;
    relatedQuery.definitionExpression = "YearTreated = " + viewYear;
    //Create table header that will go inside popup
    var content = '<table id="mgmtPopupTable1"><tr><th>Veg Mgmt Practice</th><th>Herbicide</th><th>Month</th><th>Year</th>\
                    <th>Implemented By</th><th>Funded By</th><th>Farm Bill Code</th></tr>';
    console.log("PRINTS FIRST");
    //Do query and get the attributes of each related record for the popup
    queryableMgmtTractFL.queryRelatedFeatures(relatedQuery, function (relatedRecords) {
        console.log("PRINTS THIRD");
        var fset = relatedRecords[OID].features;
        fset.forEach(function (feature) {
            var vegPractice = vegPName(feature.attributes.VegMgmtPractice);
            var herbicide = herbName(feature.attributes.Herbicide);
            var monthTreated = monthName(feature.attributes.MonthTreated);
            var yearTreated = feature.attributes.YearTreated;
            var impBy = impName(feature.attributes.ImplementedBy);
            var fundBy = fundName(feature.attributes.FundedBy);
            var fbc = feature.attributes.FarmBillCode;
            if (fundBy == "CRP" || fundBy == "CRP - CREP") {
                fbc = crpName(fbc);
            }
            else if (fundBy == "EQIP" || fundBy == "EQIP - RCPP") {
                fbc = eqipName(fbc);
            }
            else {
                fbc = "Not applicable";
            }
            row = '<tr><td>' + vegPractice + '</td><td>' + herbicide + '</td><td>' + monthTreated + '</td><td>' + yearTreated +
                '</td><td>' + impBy + '</td><td>' + fundBy + '</td><td>' + fbc + '</td></tr>';
            content = content + row;
        });
        content = content + '</table>';
    });
    console.log("PRINTS SECOND");
    return content;
}

javascript

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回答 1

Stack Overflow用户

回答已采纳

发布于 2019-02-26 15:35:58

正如我在评论中提到的，您必须等待查询完成后才能呈现内容。所以就像这样：

let content = '<table id="mgmtPopupTable1"><tr><th>Veg Mgmt Practice</th><th>Herbicide</th><th>Month</th><th>Year</th>\
                <th>Implemented By</th><th>Funded By</th><th>Farm Bill Code</th></tr>';

const render_popup = function( content ) {
    document.querySelector( '#myPopup' ).innerHTML = content;
};

// Render only the headers to begin with.
render_popup( content );

queryableMgmtTractFL.queryRelatedFeatures(relatedQuery, function (relatedRecords) {
    var fset = relatedRecords[OID].features;
    fset.forEach(function (feature) {
        ...
    });
    // Rerender the popup, now headers And content.
    render_popup( content );
});