50+ Asked Interview Questions and Answers (2024)

質問 26. Explain String functions in Javascript.

a class defines a new type (formally, Abstract Data Type)
encapsulates data (properties) and operations on that data (methods)

a String encapsulates a sequence of characters, enclosed in quotes

properties include
length : stores the number of characters in the string

methods include
charAt(index) : returns the character stored at the given index
(as in C++/Java, indices start at 0)
substring(start, end) : returns the part of the string between the start
(inclusive) and end (exclusive) indices
toUpperCase() : returns copy of string with letters uppercase
toLowerCase() : returns copy of string with letters lowercase

to create a string, assign using new or just make a direct assignment (new is implicit)

word = new String("foo"); word = "foo";

properties/methods are called exactly as in C++/Java

word.length word.charAt(0)

質問 27. Tell us about local variables.

If needed, you can declare local variables within a function.

local variable is visible only within the function body after it’s declared.

Commonly used to store results of an intermediate calculation.

function findMaxValue(num1, num2,num3) {
var tempMax; //local var

if (num1 >= num2) {
tempMax = num1;
}

else {
tempMax = num2;
}

if(num3 >= tempMax) {
tempMax = num3;
}

return tempMax;

} //end function

質問 28. Explain Global Variables in Javascript.

Global variables are those declared outside of functions
Global variables are ‘visible’ from anywhere in the program, including inside functions

var globalHello = “Hello!”;

function writeHello() {
document.write(globalHello);
}
// outputs “Hello!”

質問 29. What are primitives in Javascript?

Boolean, string and number.

質問 30. How do you submit a form using Javascript?

Use document.forms[0].submit();
(0 refers to the index of the form – if you have more than one form in a page, then the first one has the index 0, second has index 1 and so on).

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JavaScript 面接の質問と回答

関連する比較

質問 26. Explain String functions in Javascript.

質問 27. Tell us about local variables.

質問 28. Explain Global Variables in Javascript.

質問 29. What are primitives in Javascript?

質問 30. How do you submit a form using Javascript?

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