A conditional expression in JavaScript is an expression that evaluates to a boolean value and controls the execution flow based on its result. The conditional (ternary) operator ? : is used for conditional expressions.

Example Analysis:

Option A:

var result = dataCount;

This is a simple assignment, not a conditional expression.

Option B:

var result = count++ > 10;

This is a comparison but not a complete conditional expression.

Option C:

var result = dataCount++ * 1000 == 3000000;

This is an arithmetic operation followed by a comparison but not a complete conditional expression.

Option D:

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var result = count >= 10 ? "Done" : getResult();

This is a conditional (ternary) expression. If count is greater than or equal to 10, result will be "Done", otherwise, it will call getResult().

References:

MDN Web Docs - Conditional (ternary) operator

W3Schools - JavaScript Conditions