034.2 JavaScript Data Structures (weight: 3) WEB-DEVELOPMENT-ESSENTIALS Practice Questions (Page 2)

Questions 6–10

1. 6foundation · easy

   Which statement about const is true?

   • Aconst variables must be initialized at declaration.
   • Bconst variables can be reassigned if they are objects.
   • Cconst variables can be declared without initialization and assigned later.
   • Dconst variables are function-scoped.
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2. 7expert · medium

   A developer has an array of objects representing products: `const products = [{ id: 1, name: 'Laptop' }, { id: 2, name: 'Mouse' }];`. The developer needs to find the product with id 2 and update its name to 'Keyboard'. Which code correctly achieves this?

   • A`const product = products[1]; product = { ...product, name: 'Keyboard' };`
   • B`const product = products.map(p => p.id === 2); product.name = 'Keyboard';`
   • C`const product = products.find(p => p.id === 2); product.name = 'Keyboard';`
   • D`const product = products.filter(p => p.id === 2); product.name = 'Keyboard';`
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4. 8foundation · easy

   What is the key difference between primitive and complex data types?

   • AComplex types are immutable, primitives are mutable.
   • BPrimitives are stored by reference, complex types by value.
   • CPrimitives can have methods, complex types cannot.
   • DComplex types are stored by reference, primitives by value.
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5. 9foundation · easy

   Which method adds an element to the end of an array?

   • Apop()
   • Bpush()
   • Cshift()
   • Dunshift()
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6. 10foundation · easy

   Which of the following is a primitive data type in JavaScript?

   • AArray
   • BSymbol
   • CFunction
   • DObject
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