IES: JS-deck 14

Question 1

JS Operator “ %= “

Answer 1

• Performs the arithmetical operation on the two operands first
• Then assigns the results of that operation to the first variable - so that becomes its new stored value.
• Example: a%=b
• Equivalent: a=(a%b)

Question 2

JS Operator “ **= “

Answer 2

• Performs the arithmetical operation on the two operands first
• Then assigns the results of that operation to the first variable - so that becomes its new stored value.
• Example: a**=b
• Equivalent: a=(a**b)

Question 3

JS Operator “ === “

Answer 3

• Equality operator
• Compares values
• Compares if 2 operands are exactly equal (identical number values, identical characters, identical positions, identical data types, etc)
• JS is case sensitive: be aware character capitalization must match for equality
• The converse, the inequality operator “!==” employs the same rules
• Useful in comparing two values to perform “conditional branching,” where the script will follow a particular direction according to the results.
• Ex.
  1. Be aware of differing data types
  2. 25 === ‘25’ returns false
  3. 25 == ‘25’ returns true

Question 4

JS Operator “ !== “

Answer 4

• Inequality operator
• Compares values
• Compares if 2 operands are not exactly equal (unidentical number values, unidentical characters, unidentical positions, unidentical data types, etc)
• JS is case sensitive: be aware character capitalization must match for equality
• Useful in comparing two values to perform “conditional branching,” where the script will follow a particular direction according to the results.
• The converse, the equality operator “===” employs the same rules
• Ex.
  1. Be aware of differing data types
  2. 25 !== ‘25’ returns true
  3. 25 != ‘25’ returns false

Question 5

JS Operator “ == “

Answer 5

• checks for equality between two values
• Compares after performing type coercion, if necessary. (if operands are different types, JS attempts conversion to a common type before comparing)
• Useful in comparing two values to perform “conditional branching,” where the script will follow a particular direction according to the results.
• Ex.
  1. 5 == “5” string
  2. “5” converts to the number 5
  3. Script comparison eval’s to true
• Ex.
  1. Be aware of differing data types
  2. 25 == ‘25’ returns true
  3. 25 === ‘25’ returns false

Question 6

JS Operator “ != “

Answer 6

• checks for inequality between two values
• Compares after performing type coercion, if necessary. (if operands are different types, JS attempts conversion to a common type before comparing)
• Useful in comparing two values to perform “conditional branching,” where the script will follow a particular direction according to the results.
• Ex.
  1. 5 != “5” string
  2. “5” converts to the number 5
  3. Script comparison eval’s to true
• Ex.
  1. Be aware of differing data types
  2. 25 != ‘25’ returns false
  3. 25 !== ‘25’ returns true

Question 7

JS Operator “ > “

Answer 7

• “greater than” operator
• Compares 2 operands
• Returns true if the first is greater in value than the second
• Used frequently to test the value of a counter variable in a loop structure
• Conversely, the “less than” operator makes the same comparison but returns true when the first is less in value than the second

Question 8

JS Operator “ < “

Answer 8

• “less than” operator
• Compares 2 operands
• Returns true if the first is less in value than the second
• Used frequently to test the value of a counter variable in a loop structure
• Conversely, the “greater than” operator makes the same comparison but returns true when the first is greater in value than the second

Question 9

JS Operator “ >= “

Answer 9

• “greater than or equal to” operator
• Compares 2 operands
• Returns true : if the first is greater in value than the second or if the first is equal in value to the second
• [May be used frequently to test the value of a counter variable in a loop structure?]
• The converse is the “less than or equal to” operator

Question 10

JS Operator “ <= “

Answer 10

• “less than or equal to” operator
• Compares 2 operands
• Returns true : if the first is less in value than the second or if the first is equal in value to the second
• [May be used frequently to test the value of a counter variable in a loop structure?]
• The converse is the “greater than or equal to” operator

Question 11

JS string comparison trivia

Answer 11

• JS is Case-sensitive
• Thus, identical character capitalization needed for strings to be equal

Question 12

JS Operator “ && “

Answer 12

• logical operator
• AND
• Will evaluate 2 operands
• potentials (not comprehensive):
  1. yes && yes
  2. yes && no
  3. no && yes
  4. no && no
• Returns true if both operands are true
• Otherwise, will return false
• Often use in conditional branching: if both the conditions are satisfied, will follow a particular direction.
  Otherwise, it will follow a different direction.

Question 13

JS Operator “ || “

Answer 13

• logical operator
• OR
• Will evaluate 2 operands
• potentials (not comprehensive):
  1. yes || yes
  2. yes || no
  3. no || yes
  4. no || no
• Returns true if one of either operands are true
• Otherwise, will return false

Question 14

JS Operator “ ! “

Answer 14

• logical operator
• NOT
• Will evaluate one operand
• potentials (not comprehensive):
  1. !yes
  2. !no
• Returns true if single operand is false
• Otherwise, will return false
• Often use in conditional branching: if both the conditions are satisfied, will follow a particular direction.
  Otherwise, it will follow a different direction.

Question 15

JS logical operators

Answer 15

• there are only three:
  “&&” , AND
  “||” , OR
  “!” , NOT
• typically used with brands that have a Boolean value of true or false - or values that can convert to true or false

Question 16

boolean “ origin of the term “

Answer 16

• refers to a system of logical thought
• A system developed by the English mathematician George Boole (1815-1864)

Question 17

JS Operator “ The ternary operator “

Answer 17

• has 3 operands:
  1. the one before the ?
  2. The one before the :
  3. the one following the :
• syntax:
  condition ? If-true-do-this : if-false-do-this
• Examples (a variable named “flag”):
  flag = = = true ? doThis( ) : doThat( )
  flag ? str = ‘Go left’ : str = ‘Go right’
  parity = ( numTwo % 2 !== 0 ) ? ‘Odd’ : ‘Even’
• The ternary operator can return values of any data type - string, number, boolean, etc.

Question 18

JS Bitwise Operator “ | “

Answer 18

• OR
• Return a 1 in each bit where either of two compared bits is a 1
• Example:
  1010 | 0101 = 1111

Question 19

JS Bitwise Operator “ & “

Answer 19

• AND
• Return a 1 in each bit where both of two compared bits is a 1
• Example:
  1010 & 1100 = 1000

Question 20

JS Bitwise Operator “ ~ “

Answer 20

• NOT
• Return a 1 in each bit where the bit is not 1 and return 0 where the bit is 1
• Example:
  ~ 1010 = 0101