getJsonPropertyExpressions

getJsonPropertyExpressions.js

/**
 * Get an array of all possible JSON path expressions for an object.
 * 
 * @example
 * getJsonPathExpressions({
 *   "firstName": "John",
 *   "address": { "city": "Nara" },
 *   "phoneNumbers": [ { "type": "iPhone", "number": "0123-4567-8888" } ]
 * })
 * // => ["$.firstName", "$.address.city", "$.phoneNumbers[*].type", "$.phoneNumbers[*].number"]
 */
function getJsonPathExpressions(obj, expressions = [], propertyPath = "$") {
    if (typeof obj === "object" && !Array.isArray(obj)) {
        Object.entries(obj).forEach(([key, value]) => {
            const jsonPath = propertyPath + "." + key;
            if (value !== null && typeof value === "object") {
                getJsonPathExpressions(value, expressions, jsonPath);                
            } else {
                expressions.push(jsonPath);
            }
        });
    } else { // obj is an array
        const jsonPath = propertyPath + "[*]";
        if (obj.length) {
            const firstElement = obj[0];
            if (firstElement !== null && typeof firstElement === "object") {
                getJsonPathExpressions(firstElement, expressions, jsonPath);
            } else {
                 expressions.push(jsonPath);
            }
        } else {
            expressions.push(jsonPath);
            console.warn(`Empty array for path ${propertyPath}.`);
        }
    }
    return expressions;
}