calculator app using vanilla js

Tried to handle calculation syntax error 🤯 like windows calculator does.

This challenge became little challenging when I was trying - calculator will automatically turn the incorrect syntax into correct syntax, like the use cases:

• user pressing equal key (=) without giving operator and operands
• user just input single operand and then pressing equal key(=)
• user input an operand that has only decimal point but no digit
• one calculation is just finished but user again pressing equal key without giving any input
• user input operator(+,-,/*) without inserting operands
• user using the calculation result as a the first operand

please know me your feedback, any suggestions, bugs