Once the web3 object is correctly created and simplecontractinstance is created, calls to the contract functions can be made easily. example: function callMatchertrue() var txn = simplecontractinstance.Matcher.call(12); }; console.log(“return value: ” + txn); function callMatcherfalse() var txn = simplecontractinstance.Matcher.call(1);{ }; console.log(“return value: ” + txn); Calls can be made using simplecontractinstance.Matcher.call and then by passing the value for the argument.
Recall the Matcher function in solidity code: function Matcher (uint8 x) returns (bool) It takes one argument x of type uint8 and returns a Boolean value, either true or false.
A Complete Guide to Understanding This Blockchain Concept
Accordingly, the call is made to the contract, as shown here: var txn = simplecontractinstance.Matcher.call(12); In the preceding example, console.log is used to print the value returned by the function call.
Once the result of the call is available in the txn variable, it can be used anywhere throughout the program, for example, as a parameter for another JavaScript function.
Finally, the HTML file named index.html is created with the following code:
Alternatively, the file can be browsed from the filesystem but that can cause some issues related to serving the content correctly with larger projects; as a good practice, always use a web server.
A quick web server in Python can be started using the following command.
This server will serve the HTML content from the same directory that it has been run from.
Why This Matters for Blockchain Technology
The Python web server is not necessary; it can be an Apache server or any other web container: $ python -m SimpleHTTPServer 7777 Serving HTTP on 0.0.0.0 port 7777 …
Now any browser can be used to view the web page served over TCP port 7777.
It should be noted that the output shown here is in the browser’s console window.
The browser’s console must be enabled in order to see the output.
Key Points to Remember
- Recall the Matcher function in solidity code: function Matcher (uint8 x) returns (bool) It takes one argument x of type uint8 and returns a Boolean value, either true or false.
- Accordingly, the call is made to the contract, as shown here: var txn = simplecontractinstance.Matcher.call(12); In the preceding example, console.log is used to print the value returned by the function call.
- Once the result of the call is available in the txn variable, it can be used anywhere throughout the program, for example, as a parameter for another JavaScript function.
- Alternatively, the file can be browsed from the filesystem but that can cause some issues related to serving the content correctly with larger projects; as a good practice, always use a web server.
Going Deeper: Advanced Concepts
For example, in Chrome you can use keyboard shortcuts to open console.
On Windows and Linux: Ctrl + Shift + J, and on Mac: Cmd + Option + J are used:
Conclusion
Contract functions represents one of the many innovative layers that make blockchain technology so powerful and transformative. As distributed systems continue to evolve, a solid understanding of these core concepts becomes increasingly valuable — not just for developers, but for anyone building, investing in, or working alongside blockchain-powered systems.
Whether you are just starting your blockchain journey or deepening existing expertise, mastering these fundamentals gives you the tools to think clearly about decentralized systems and make smarter decisions in this rapidly evolving space.