How Can I Dynamically Set Nested Property Values in JavaScript Objects Using a String Path?

Dynamic Property Setting in JavaScript Objects

Suppose we're given an object obj and a property name stored as a string propName, where propName can represent nested properties, such as "foo.bar.foobar."

Problem: How can we dynamically set the value of obj.foo.bar.foobar using propName as the path?

Solution: We can use the assign function below to set the property value dynamically:

function assign(obj, prop, value) {
    // Convert the string property name into an array of nested levels
    if (typeof prop === "string")
        prop = prop.split(".");

    // Check if the current level is the last (length == 1) or nested
    if (prop.length > 1) {
        // Shift the first level of nesting (e.g., "foo")
        var e = prop.shift();
        // Recursively call `assign` on the child object (e.g., obj.foo)
        assign(obj[e] =
                 Object.prototype.toString.call(obj[e]) === "[object Object]"
                 ? obj[e]
                 : {},
               prop,
               value);
    } else
        // For the last level, set the value directly
        obj[prop[0]] = value;
}

Usage:

// Object to modify
var obj = {};
// String representing the nested property path
var propName = "foo.bar.foobar";
// Value to set
var newValue = "hello world";

// Call the `assign` function to dynamically set the property value
assign(obj, propName, newValue);

// Check the updated value (for debugging purposes)
console.log(obj.foo.bar.foobar); // Output: "hello world"

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