JavaScript is a dynamically typed language, which means the types of variable can be changed during runtime. Many interview questions involve recursion of values that contain values of different types and how to handle each value type differs according to the type (e.g. different code is needed to iterate over an array vs an object). Knowledge of handling the JavaScript types is crucial to solving questions like Deep Clone and Deep Equal.
In this question, we will implement the following utility functions to determine the types of primitive values.
isBoolean(value)
: Return true
if value
is a boolean, false
otherwise.isNumber(value)
: Return true
if value
is a number, false
otherwise. Note that NaN
is considered a number.isNull(value)
: Return true
if value
is null
, false
otherwise.isString(value)
: Return true
if value
is a String
, else false
.isSymbol(value)
: Return true
if value
is a Symbol
primitive, else false
.isUndefined(value)
: Return true
if value
is undefined
, else false
.