Implement JSONPathParser

randomwallpaper@iflow.space/jsonpath/jsonpath.js

@@ -0,0 +1,136 @@
+let JSONPathParser = function () {
+
+	/**
+	 * Access a simple json path expression of an object.
+	 * Returns the accessed value or null if the access was not possible.
+	 *
+	 * @param inputObject the object to access
+	 * @param inputString the json path expression
+	 * @returns {*}
+	 */
+	this.access = function(inputObject, inputString) {
+		if (inputObject === null || inputObject === undefined) {
+			return null;
+		}
+
+		if (inputString.length === 0) {
+			return inputObject;
+		}
+
+		let startDot = inputString.indexOf('.');
+		if (startDot === -1) {
+			startDot = inputString.length;
+		}
+
+		let keyString = inputString.slice(0, startDot);
+		let inputStringTail = inputString.slice(startDot+1);
+
+		let startParentheses = keyString.indexOf('[');
+
+		if (startParentheses === -1) {
+
+			if (!keyString.empty && !inputObject.hasOwnProperty(keyString)) {
+				return null;
+			}
+
+			return this.access(inputObject[keyString], inputStringTail)
+
+		} else {
+
+			let indexString = keyString.slice(startParentheses+1, keyString.length-1);
+			keyString = keyString.slice(0, startParentheses);
+
+			if (!keyString.empty && !inputObject.hasOwnProperty(keyString)) {
+				return null;
+			}
+
+			switch (indexString) {
+			case "@random":
+				return this.access(this.randomElement(inputObject[keyString]), inputStringTail);
+				// add special keywords here
+			default:
+				// expecting integer
+				return this.access(inputObject[keyString][parseInt(indexString)], inputStringTail);
+			}
+
+		}
+
+	};
+
+	/**
+	 * Returns the value of a random key of a given object.
+	 *
+	 * @param inputObject
+	 * @returns {*}
+	 */
+	this.randomElement = function(inputObject) {
+		let keys = Object.keys(inputObject);
+		let randomIndex = Math.floor(Math.random()*keys.length);
+
+		return inputObject[keys[randomIndex]];
+	}
+
+};
+
+/*
+	Tests
+ */
+
+let parser = new JSONPathParser();
+
+let accessString = "naise";
+let object = {naise: "one"};
+let val;
+
+console.log(`Accessing "${accessString}"`);
+val = parser.access(object, accessString);
+console.log(`Value: ${val}`);
+console.log(`=================`);
+
+accessString = "going.deep.anyArrayOrObject[1].someKey";
+object = {
+	naise: "one",
+	going: {
+		deep: {
+			anyArrayOrObject: [
+				{someKey: "I am 1!"},
+				{someKey: "I am 2!"},
+				{someKey: "I am 3!"},
+				{someKey: "I am 4!"},
+				{someKey: "I am 5!"},
+				{someKey: "I am 6!"},
+				{someKey: "I am 7!"},
+				{someKey: "I am 8!"},
+			]
+		}
+	}
+};
+
+console.log(`Accessing "${accessString}"`);
+val = parser.access(object, accessString);
+console.log(`Value: ${val}`);
+console.log(`=================`);
+
+accessString = "going.deep.anyArrayOrObject[@random].someKey";
+object = {
+	naise: "one",
+	going: {
+		deep: {
+			anyArrayOrObject: [
+				{someKey: "I am 1!"},
+				{someKey: "I am 2!"},
+				{someKey: "I am 3!"},
+				{someKey: "I am 4!"},
+				{someKey: "I am 5!"},
+				{someKey: "I am 6!"},
+				{someKey: "I am 7!"},
+				{someKey: "I am 8!"},
+			]
+		}
+	}
+};
+
+console.log(`Accessing "${accessString}"`);
+val = parser.access(object, accessString);
+console.log(`Value: ${val}`);
+console.log(`=================`);