How to access nested JSON property based on another property's value in JavaScript?

To access nested JSON property based on another property’s value, the code is as follows −

Example

var actualJSONData = JSON.parse(studentDetails()),
studentMarks = getMarksUsingSubjectName(actualJSONData, "JavaScript");
console.log("The student marks="+studentMarks);
function getMarksUsingSubjectName(actualJSONData, givenSubjectName){
   for(var tempObj of actualJSONData){
      if(tempObj.subjectName = givenSubjectName){
         return tempObj.marks;
      }
   }
}
function studentDetails(){
   return JSON.stringify(
      [
         { firstName : "John", subjectName: "JavaScript", marks : 97 },
         { firstName : "David", subjectName: "Java", marks : 98 }
      ]
   );
}

To run the above program, you need to use the following command −

node fileName.js.

Here, my file name is demo155.js.

Output

This will produce the following output −

PS C:\Users\Amit\JavaScript-code> node demo155.js
The student marks=97