Allow avoiding autostart with optionally separate call to new public method, "evaluate"

lib/jsonpath.js

@@ -37,25 +37,34 @@ function JSONPath (opts, obj, expr) {
     if (!(this instanceof JSONPath)) { // Make "new" optional
         return new JSONPath(opts, obj, expr);
     }
-    this.obj = obj;
-    var self = this;
 
-    var resultType = (opts && opts.resultType.toLowerCase()) || 'value';
-    var flatten = (opts && opts.flatten) || false;
-    var wrap = (opts && opts.hasOwnProperty('wrap')) ? opts.wrap : true;
-    this.sandbox = (opts && opts.sandbox) ? opts.sandbox : {};
+    opts = opts || {};
+    this.resultType = (opts.resultType && opts.resultType.toLowerCase()) || 'value';
+    this.flatten = opts.flatten || false;
+    this.wrap = opts.hasOwnProperty('wrap') ? opts.wrap : true;
+    this.sandbox = opts.sandbox || {};
+
+    if (opts.autostart !== false) {
+        return this.evaluate(obj, expr);
+    }
+}
+
+// PUBLIC METHODS
 
-    if (expr && obj && (resultType === 'value' || resultType === 'path')) {
+JSONPath.prototype.evaluate = function (obj, expr) {
+    var self = this;
+    this.obj = obj;
+    if (expr && obj && (this.resultType === 'value' || this.resultType === 'path')) {
         var exprList = this._normalize(expr);
         if (exprList[0] === '$' && exprList.length > 1) {exprList.shift();}
         var result = this._trace(exprList, obj, ['$']);
         result = result.filter(function (ea) { return ea && !ea.isParentSelector; });
-        if (!result.length) {return wrap ? [] : false;}
-        if (result.length === 1 && !wrap && !Array.isArray(result[0].value)) {return result[0][resultType] || false;}
+        if (!result.length) {return this.wrap ? [] : false;}
+        if (result.length === 1 && !this.wrap && !Array.isArray(result[0].value)) {return result[0][this.resultType] || false;}
         return result.reduce(function (result, ea) {
-            var valOrPath = ea[resultType];
-            if (resultType === 'path') {valOrPath = self._asPath(valOrPath);}
-            if (flatten && Array.isArray(valOrPath)) {
+            var valOrPath = ea[self.resultType];
+            if (self.resultType === 'path') {valOrPath = self._asPath(valOrPath);}
+            if (self.flatten && Array.isArray(valOrPath)) {
                 result = result.concat(valOrPath);
             } else {
                 result.push(valOrPath);
@@ -63,7 +72,9 @@ function JSONPath (opts, obj, expr) {
             return result;
         }, []);
     }
-}
+};
+
+// PRIVATE METHODS
 
 JSONPath.prototype._normalize = function (expr) {
     if (cache[expr]) {return cache[expr];}