I am working on customizing the JSON.parse function by using the optional reviver argument to specify that I want the calc(string) function to focus on a key named "expr" within the input string. Once that key is processed, the function should then operate on the remaining portion of the string.
However, whenever I run this code, I keep receiving a NaN result.
Interestingly, if I disable the last two calls to calc(string) just before the console.log(initNumber) statement, the program performs as intended.
In essence, I want the function to recognize the key "expr" and carry out specific operations based on the nested "op" key within it. For example, if the "op" key has a value of "add", the function should execute the add() function on the nested object. The same principle applies if the "op" key is "subtract".
Any assistance would be greatly valued.
var initNum = 0;
var calc = function(string) {
var calcString = JSON.parse(string, reviver);
add(calcString);
subtract(calcString);
};
var add = function(string) {
if (string["op"] == "add") {
var numString = parseInt(JSON.stringify(string["number"]));
initNum = numString + initNum;
return initNum;
}
}
var subtract = function(string) {
if (string["op"] == "subtract") {
var numString = parseInt(JSON.stringify(string["number"]));
initNum = initNum - numString;
return initNum;
}
}
var reviver = function(key, val) {
if (key == "expr") {
if (val.op == "add") {
return add(val);
}
else if (val.op == "subtract") {
return subtract(val);
}
}
else {
return val;
}
};
calc('{"op" : "add", "number" : 5}');
calc('{"op" : "subtract", "number" : 2}');
calc('{"op" : "add", "number" : 19}');
calc('{"op": "subtract", "expr" : {"op" : "add", "number" : 15}}');
calc('{"op": "add", "expr" : {"op" : "add", "expr" : {"op" : "subtract", "number" : 3}}}');
console.log(initNum);