This is a javascript ES5 parser and interpreter written entirely in dart.

What it is

• Primary use case is to let users type in simple js that you want to execute inline. This should be not used as a general replacement for dart in flutter
• Runs in the same process as your Dart/Flutter code so no need to use the browser's javascript engine. As a result, this is fast.
• Unlike react native, doesn't require any bridge or have memory issues
• Supports most common use cases right now such as functions, lists, all primitive types (string, number, arrays, dates) etc.
• Highly extensible. The context object could be json or any dart object enhanced with the Invokable mixin (see below)

How to use

• in your pubspec.yaml, add the following line under dependencies -

  ensemble_ts_interpreter:
    git:
      url: https://github.com/EnsembleUI/ensemble_ts_interpreter.git
      ref: master

• run flutter pub upgrade
• Simply call the JSInterpreter with the code you want to evaluate while passing it the context.

JSInterpreter.fromCode(code, context).evaluate();

context is the key object here. You can pass json as context (see examples below) or pass an instance of Invokable which could be any Dart object.

Examples

All the examples are in the unit test suite - new_interpreter_tests

Listing some here.

Filter a list

    Map<String, dynamic> context = {
      'items': ['one', 'two', 'three'],
      'nested': [
        {'id': 1, 'label': 'eggs', 'type': ''},
        {'id': 2, 'label': 'strawberry', 'type': 'fruit'},
        {'id': 3, 'label': 'nut'}
      ]
    };

    String code = """
      var flatList = items.filter(function(e) {
        return e != 'two';
      });
      
      var nestedList = nested.filter(function(e) {
        return e['type'] == 'fruit'
      });
    """;
    
    JSInterpreter.fromCode(code, context).evaluate();

Different String functions

    Map<String, dynamic> context = initContext();

    String code = """
        var arr = ['a','b','c','d'];
        var b = arr.at(1);
        var arr2 = arr.concat(['e','f']);
        var f = arr2.find(function (element)  { 
              var rtn = ( element == 'f' )? true : false;
              return rtn;
         });
         var includes = arr2.includes('e');
         var str = arr.join();
         var str2 = arr.join('-');
         var str3 = arr.join('');
         var last = arr2.pop(); 
         var nums = [1,2,3,4,5];
         var sum = nums.reduce(function (value, element) {
            return value + element;
            });
         var reversed = arr.reverse();
        """;

    JSInterpreter.fromCode(code, context).evaluate();

Function Declaration and then calling the functions

  test('functiondeclarationtext', () async {
    String codeToEvaluate = """
      var i = 0;
      var users = [{'name':'Khurram'},{'name':'Mahmood'}];
      updateSalary(users,noArgFunction());
      return manyParms(users[0],noArgFunction()[0],'Hello','How','are','you','today,');
      function noArgFunction() {
        var salaries = [10000,200000];
        salaries[1] = 900000;
        return salaries;
      }
      function updateSalary(users,salaries) {
        users.map(function(user) {
          user['salary'] = salaries[i];
          user['age'] = age;
          i++;
        });
      }
      function manyParms(user,salary,a,b,c,d,e) {
        return a+' '+b+' '+c+' '+d+' '+e+' '+user.name+'. You made \$'+salary;
      }
        
      """;
    Map<String, dynamic> context = initContext();
    dynamic rtnValue = JSInterpreter.fromCode(codeToEvaluate,context).evaluate();
    expect(context['users'][0]['name'],'Khurram');
    expect(context['users'][0]['salary'],10000);
    expect(context['users'][1]['salary'],900000);
    expect(context['users'][1]['age'],3);
    expect(rtnValue,'Hello How are you today, Khurram. You made \$10000');
  });