safe-evaluate-expression - npm Package Compare versions

Comparing version 1.0.3 to 1.0.4

index.js

 //**************************************************************
-// RegEx to find all parameters in function and sub-function
+// RegEx to find  parameters, comments and arguments
 //**************************************************************
-const findParams = /\b\w+(\b(?!\())/g;
+const FUNC_PARAMS = /\b\w+(\b(?!\())/g;
+const STRIP_COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/gm;
+const ARGUMENT_NAMES = /([^\s,]+)/g;
 
 //**************************************************************
+// Returns regular function parameters names
+//**************************************************************
+function getParamNames(func) {
+  const fnStr = func.toString().replace(STRIP_COMMENTS, "");
+  const result = fnStr.slice(fnStr.indexOf("(") + 1, fnStr.indexOf(")")).match(ARGUMENT_NAMES);
+
+  return result || [];
+}
+
+//**************************************************************
+// Returns labda function body
+//**************************************************************
+function getLambdaBody(func) {
+  const fnStr = func.toString().replace(STRIP_COMMENTS, "");
+  return fnStr.substring(fnStr.indexOf("=>") + 3);
+}
+
+//**************************************************************
 // Wrap a param in a try-catch to handle undefined params
 //**************************************************************
-const makeSafeParam = (param) => `(() => {
+const makeSafeParam = (param, undef) => `(() => {
       try {
-        return ${param};
+        return ${param} !== undefined ? ${param} : ${undef};
       } catch (e) {
-        return undefined;
+        return ${undef};
       }
@@ -21,3 +41,3 @@ })()`;
 //**************************************************************
-const makeSafe = (str) => str.replace(findParams, (p) => makeSafeParam(p));
+const makeSafe = (str, undef) => str.replace(FUNC_PARAMS, (p) => makeSafeParam(p, undef));
 
@@ -28,3 +48,3 @@ //**************************************************************
 //**************************************************************
-const evaluate = (body, params) => {
+const evaluate = (body, params, undef) => {
   const input = `{${Object.keys(params)
@@ -34,6 +54,23 @@ .map((k) => k)
 
-  const func = new Function(input, `return ${makeSafe(body)}`);
+  const func = new Function(input, `return ${makeSafe(body, undef)}`);
   return func(params);
 };
 
+//**************************************************************
+// Get a lambda function as input and optiona parameters
+// to default undefined params in returnd function
+//**************************************************************
+function defaultLambda(func, undef) {
+  const expression = getLambdaBody(func).trim();
+  const names = getParamNames(func);
+
+  return function (...vars) {
+    const params = {};
+    names.forEach((name, index) => (params[name] = vars[index]));
+
+    return evaluate(expression, params, undef);
+  };
+}
+
 module.exports = evaluate;
+module.exports.defaultLambda = defaultLambda;

package.json

 {
   "name": "safe-evaluate-expression",
-  "version": "1.0.3",
+  "version": "1.0.4",
   "description": "Small library to dynamically create and evaluate expression with multiple parameters (even undefined)",
@@ -5,0 +5,0 @@ "main": "index.js",

README.md

 # safe-evaluate-expression
 
-Small library to dynamically create and evaluate expression with multiple parameters (even undefined).
+Small library to dynamically create and evaluate expression with multiple parameters (even undefined). _It also offer an ancillary function to protect lambda function to undefined params inputs._
 
@@ -11,2 +11,6 @@ ## Installation
 
+## Usage
+
+### _evaluate(expression:[String], params:[Object])_
+
 ## Example
@@ -43,1 +47,18 @@
 ```
+
+## Default lambda undefined params
+
+### _protectedLambda(lamdaFunc, [undefined dafalut])_
+
+Protect lambda function by assigning a default value for undefined input paramters.
+
+```javascript
+const { defaultLambda } = require("safe-evaluate-expression");
+
+const lambda = (a, b, c) => a + b + c;
+const protectedLambda = defaultLambda(lambda, 0);
+
+// The unprotected lambda returns NaN because all values are undefined
+// The protected one return zero (default): 0 + 0 + 0
+console.log(lambda(), protectedLambda()); // -> NaN 0
+```

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Improved metrics

Total package byte prevSize

17512

increased by21%

Number of package files

5

increased by25%

Lines of code

86

increased by177.42%

Number of lines in readme file

63

increased by50%

No dependency changes