function 中的 array.push(item)

Question

I want to push all volume to arrayVolume but can't. In my opinion the problem is asynchronous. But I search, read document but can't do it run correct. Please help me solve the code if you can. That is my gratitude to you. Many thanks!

function kl(data){
    var arrayVolume = [];
    for(var key in data){
        var dbId = data[key];
        viewer.getProperties(dbId, function(e){
            var propertiesObj = e.properties;
            propertiesObj.forEach(myF);
            function myF(obj){
                if(obj.displayName === "Volume"){
                    var volume = obj.displayValue;
                    arrayVolume.push(volume);
                }
            }
        });
    }
    alert(arrayVolume);
}

Answer 1

If that viewer.getProperties is an async operation, like an http call, you should use promises.

For example:

async function kl(data) {
    var arrayVolume = [];

    for (var key in data) {
        var dbId = data[key];
        await new Promise((resolve, reject) => {
            viewer.getProperties(dbId, (e) => {
                var propertiesObj = e.properties;

                propertiesObj.forEach(myF);

                function myF(obj) {
                    if (obj.displayName === "Volume") {
                        var volume = obj.displayValue;

                        arrayVolume.push(volume);
                    }
                }

                return resolve();
            });
        });
    }
    
    alert(arrayVolume);
}

Answer 2

I have the same problem again here. How can I deal with it. Actually I still can't understand async await promises. klht return no object. @Ali Demirci

        var klht = [];
    dataViewerFirst.forEach(obj => {
        var externalId = obj.externalId;
        var _projectName = obj.projectName;
        var status = obj.status;
        if(externalId !== null && externalId !== undefined && _projectName === projectName && status === 1){
            
            viewer.model.getExternalIdMapping(data => first(data));
            async function first(data){
                dbId = data[externalId];
                await new Promise((resolve, reject) => {
                    viewer.getProperties(dbId, function(e){
                        var propertiesObj = e.properties;
                        propertiesObj.forEach(myF);
                        function myF(obj){
                            if(obj.displayName === "Volume"){
                                var volume = obj.displayValue;
                                klht.push(volume);
                                console.log('vol '+volume);
                            }
                        }
                        return resolve();
                    });
                    
                })
                //return resolve();
            }
        }
    })
    console.log('v '+klht);