Predict the output of the following javascript code

varx=5,y=1  
var obj ={ x:10}  
with(obj)  
{  
      alert(y)  
}

 

 

 

 

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Quiz Explanation

This JavaScript code seems to have a syntax error and an unexpected behavior due to the usage of with statement, which is generally discouraged because it can lead to confusing and error-prone code.

Let's correct the syntax and explain the behavior:

var x = 5, y = 1; // Corrected variable declaration with comma separation
var obj = { x: 10 }; // Corrected variable declaration with semicolon
with (obj) {
    alert(y); // Alerts 'undefined' because 'y' is not a property of 'obj'
}

In this corrected code:

  • Two variables x and y are declared and assigned values 5 and 1 respectively.
  • An object obj is defined with a property x set to 10.
  • The with statement is used to temporarily extend the scope chain to include the properties of obj.
  • Inside the with block, it tries to access the variable y which is not a property of obj. So, it will alert undefined.

Overall, using with statement is generally not recommended due to its potential for confusion and bugs, and it's better to access object properties directly.