Nested forEach loop does not work

Question

I have some data that is in JSON object array. I'm trying to use nested forEach loops to extract the data.

The data is modeled like belo. There's multiple dataModels and multiple childNodes inside the dataModels.

//this is what an example data looks like
dataModels[0].childNodes[0].appId

I am trying to do something like the following:

dataModels.forEach(function(entry){
    entry.forEach(function(childrenEntry){
      console.log(childrenEntry.appId);
    })
})

The above however does not work and it gives me an error saying that 'entry' is not a function. Is there a better way to achieve what I'm trying to do?

Answer 1

You are not targeting the array inside the entry object, you need to loop over the childNodes property in order to get the data you want. See example below.

var dataModels = [];

dataModels[0] = {
    childNodes: []
};

dataModels[0].childNodes[0] = {
    appId: "foo"
};

dataModels.forEach(function(entry){ 
    entry.childNodes.forEach(function(childrenEntry) { // was missing a )
      console.log(childrenEntry.appId);
    });
});

JsFiddle demo

Answer 2

Nesting foreach is really a bad practice. Instead of that you can use the map() function to get data.

Suppose a array of object be like this & now here how to use map instead of multiple foreach();

data = [{
    dataModels: [{
        childNodes: {
            appId: 'foo'
        }
    }]
}];


data.forEach(function(obj) {
    var res = obj.dataModels.map(function(o) {
        return o.childNodes;
    });
    console.log(res[0]);
});