Whenever I try to perform string operations on variables that contain the values of object's properties in Javascript, I get an error about the interpreter not being able to find whatever the method Im trying to use for that object: 

```
var arrOfEntries = {};

arrOfEntries["name1"] = "Jane" ;
arrOfEntries["age1"] = "40" ;
arrOfEntries["name2"] = "Kathy" ;
arrOfEntries["age2"] = "35" ;
arrOfEntries["name3"] = "Mary" ;
arrOfEntries["age3"] = "23" ;
arrOfEntries["name4"] = "Donna" ;
arrOfEntries["age4"] = "32" ;

var result = ' ';
for (prop in arrOfEntries) {
    var tempVar = String(prop) /*/this line was added as an attempt to force the property into the type String, but does not work*
    if (tempVar.includes("name"))
        result += tempVar
    }

```

In this case, I simply wish to check for the existence of the string "name" within the name of each property of that object and then collect only these properties for further actions. What am I missing here?