CODEWITHSUNDEEP
javascriptmetadatametaprogrammingsapui5
Gana
Gana

Reputation: 492

Read Java Script function argument data type infomation

Is it possible to read a java script function arguments and their type information?

For example, i have a class below:

    sap.ui.define( ['sap/ui/core/theming/Parameters'],
            function(P){
                'use strict';
            var B=C.extend('sap.m.Button', { 
                            metadata:{
                                properties:{
                                text:{
                                    type:'string',
                                    group:'Misc',
                                    defaultValue:null
                                },
                                type:{
                                    type:'sap.m.ButtonType',
                                    group:'Appearance',
                                    defaultValue:sap.m.ButtonType.Default
                                }
                            }
                        } );

.....B.prototype.setType=function(t){this.setProperty('type',t);....

......lot of code exposes public setter & getter methods for the above properties.......
                        } );

Complete code of the class can be accessed from here.

I am able to read the method names from the public methods exposed by the class. But this does not allow me to know the arguments and their type information.

For example: B.prototype.setType is a public method exposed. I can acquire an object of Button class but not getting an idea of how to read its argument type info in run time.

If I want to let the user to add value for "type" property (it is button type), i should know the type of value he can enter.

How can i achieve this?

Thanks

Edit 1:

In my first step, i am using getMetadata() method of sap.m.Button class which is exposed by the framework and this gives me the publicMethodNames but it does not give me information about argument type information. So, i am looking for alternatives.

In java, for this kind of need, we have reflection API. How can we achieve the same in javascript?

Edit 2: A screenshot illustrating the result achieved in an IDE.

enter image description here

Upvotes: 2

Views: 92

Answers (1)

Digger2000
Digger2000

Reputation: 546

You can access to function parameters with arguments object:

var f = function () {
  for (var i = 0; i < arguments.length; i++) {
    console.log(arguments[i], typeof arguments[i]);  
  }
}

f(123, 'test', { a: 1}, function () { alert('x') });

UPD How to get declared arguments number:

var f = function (a, b) {
  console.log(arguments); 
};

console.log(f.length); //2
f(1, 1, 1, 1); //object with 4 keys
f(1); //object with 1 key

Upvotes: 1

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