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  • 🔰HTML
    • 🔰element
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        • type="range"
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  • 🔰CSS
    • ⭐box model
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        • center with "transform"
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    • 🔰values
      • 🔰units
        • 🔰相對單位
          • 🔸percentage (％)
          • 🔸rem
          • 🔸em
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        • radial-gradient()
    • 🔰variables
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      • 🔹calc()
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      • select direct children by JS
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  • 🍒JS
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    • 🧚technique
    • ⭐feature
      • ⭐️ ES5
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    • 🔰concept
      • 🔰execution context
        • 📘this
          • ❗"this" determined on call site❗️
        • 🔰running execution context
        • 🔰lexical environment
          • 🔰environment record
          • 🔸[[Environment]]
          • ❗lexical environment optimizaton
        • 🔰call stack
      • 🔰context
        • 🔰global context
        • 🔰class body context
      • 🔰environment
        • ⚙️JS engine
          • 🔰mode
            • 🛡️strict mode
              • 🛡️eval has its own scope in strict mode
              • ✅always use strict mode
            • ❗sloppy mode
              • ❗accidental global variable in sloppy mode❗️
              • ❗modify current scope at runtime❗️
            • ⚖️strict vs. sloppy
          • 🔰v8
        • 🔰Node.js
      • 🔰associated array
      • 🔰parser
    • 🔰compilation
      • 🔰lexing
      • 🔰parsing
      • 🔰code generation
      • 🔰JS is compiled
      • 🔰compile-time
      • 🔰runtime
    • 🔰grammar
      • 🚩directive
        • 📜'use strict'
      • *️token
        • 🗝️keyword
          • 🔐reserved word
            • ❗reserved word as property name is allowed❗️
          • 🔑contextual keyword
        • 🔣punctuator
          • *️hash (#)
          • 🔣semicolon (;)
            • 🔰automatic semicolon insertion
            • 🔰statements that must end with ";"
          • 🔣dot (.)
          • 🔣comma (,)
          • 🔣colon (:)
          • 🔣plus (+)
          • 🔣equal (=)
          • 🔣3 dots (...)
          • 🔣brackets []
          • 🔣braces {}
          • 🔣parentheses ()
          • 🔣question dot (?.)
          • 🔣question (?)
        • 🆔identifier
          • 🆔special identifier
          • ⚖️identifier vs. string
          • ⚖️identifier vs. keyword
          • ❗undeclared identifier
          • 🔰static binding
          • 🔰dynamic binding
        • ✡️literal
          • 🔰trailing comma
      • 🔰comment
      • 🈯declaration
        • ❗redeclaration
        • 🈯lexical declaration
      • 📜statement
        • 📦expression
          • 📦primary expression
          • 📦invocation expression：f()
            • 📦method invocation
          • 📦left-hand side expression
        • 🔁loop
          • 🔁while
          • 🔁do...while
          • 🔁for loops
            • 🔁for
              • 🔰"for-init" scope
              • 🔰"for-init" block
            • 🔁for-in
            • 🔁for-of
              • ❗arrays are iterated "live"❗️
              • 🔰for-of with objects
              • 🔰for-of with strings
              • ⚖️for-of vs. forEach
            • 🔁for-await
            • ⚖️for-in vs. for-of vs. in
            • 📘arr.forEach()
        • 🔀control flow
          • ⤴️jump
            • ⤴️return
            • ⤴️continue
            • ⤴️break
            • ⚖️continue vs. break
          • 🔀branch
            • 🔀if
            • 🔀switch
              • 🔀case clause
        • 📜other statement
          • 📜block
            • 🔰block scope
          • 📜label
          • 🛑with
          • 📜empty statement
        • ⛔statement expected❗️
      • 🚧operator
        • 🚧table of operators
        • 📖terms for operator
          • 🔰arity
          • 🔰associativity
          • 🔰lvalue
          • 🔰dividend
          • 🔰divisor
          • 🔰non-numeric operand
          • 🔰short-circuiting
        • 🔴assignment
          • ⭐destructuring assignment
            • 🔰destructuring array
            • 🔰destructuring iterable
            • 🔰object destructuring
            • 🔰nested destructuring
              • 🌟nested default values
            • 🔰destructuring arguments
          • ➕assignment (=)
        • 🔴arithmetic operator
          • ⭕unary arithmetic operator
            • 🚧unary plus (+)
          • ⭕binary arithmetic operator
            • ➕add/concate (+)
            • ➕division (/)
            • ➕remainder (%)
              • 💾modulo(a, b)
              • 💾mod(a, b)
              • ⚖️remainder vs. modulo vs. mod
            • ➕exponentiation (**)
          • ⭕bitwise operator
            • 🌟2's complement
            • 💾bitview()
            • ➕bitwise not (~)
              • 🔰double tilde (~~)
              • ⚖️(~~) vs. Math.trunc()
        • 🔴relational operator
          • 🔰equality & inequality operator
            • ➕sloppy equality (==)
            • ➕strict equality (===)
          • 🔰comparison operator
          • ➕in
          • ➕instanceof
        • 🚧logical operator
          • ➕nullish coalescing (??)
          • ⭕unary logical operator
          • ⭕binary logical operator
        • ⭕unary operator
          • ➕void
        • ⭕binary operator
          • ➕comma operator (,)
        • ⭕ternary operator
          • ➕conditional operator (?:)
        • 🔰spread operator (...)
        • ➕rest operator (...)
      • 🔰statement vs. declaration
    • 🔰scope
      • 🔰lexical scope
      • 🔰static scope
      • 🔰dynamic scope
      • ⚖️static vs. dynamic scoping
      • 🔰scope chain
      • ⚖️lexical environment vs. scope
      • 🔰top-level scope
      • 🌟global scope
        • 📘global object
          • 🏷️globalThis
          • 🍄window
            • 🔸window.name
            • 🔸window.navigator
          • 🍄global
          • 🔸eval
          • 🔸global object property
        • 💾isCurrentlyInGlobalScope()
        • 🔰global variable
          • 🔰global let
            • ❗global let shadows global object property
          • 🔰global var
        • 🔸DOM element with "id"
      • 🔰module scope
      • 🔰function scope
      • 🔰function name scope
      • 🔰parameter scope
      • 🔰hoisting
        • 🔰function hoisting
          • ❗function hoisting first❗️
        • 🔰variable hoisting
          • 🔰var hoisting
            • ❗function expression not hoisted
          • 🔰let/const/class hoisting
      • ⚖️context vs. scope
    • 💍value
      • 🔰type
        • 💍falsy
        • 📖terms for type
          • 🔰statically typed
          • 🔰dynamically typed
        • 🔰type conversion
        • 🔰type name
          • ➕typeof
          • 💾baseTypeName()
          • 💾typeName()
          • 💾custom type name
        • 🔰nested type
        • 👔type functions
          • 💾functionDefinition()
          • 💾isObject()
          • 💾isPrimitive()
          • 💾isFunction()
          • 💾isClass()
      • 🦠primitive
        • 💍nullish
        • 🔸undefined
        • 🔐null
        • 🔢Number
          • 🔰floating-point
          • 🔰integers
          • 🔴special number
            • 🔢Infinity
            • 🔢NaN
            • 🔢Number.EPSILON
            • 🔢Number.MAX_VALUE
            • 🔢Number.MAX_SAFE_INTEGER
          • 👔Number+ext
            • 💾n.toHex()
            • 💾n.isEqual()
            • 💾isNumber()
          • 👔Random
            • randomInt()
            • randomFloat()
          • 👔Quaternion
        • 🔢BigInt
        • 🦠Boolean
        • 🔤String
          • 🔰raw string
          • 🔰escape sequence
          • template literal
            • tagged template
            • tag function
          • 🔰String methods
            • str.map()
            • 💾str.capitalize()
            • str.countLetters()
            • 💾str.htmlToElement()
            • str.kebabToCamelCase()
            • 📘str.match()
              • ✨split into course names
            • 📘str.matchAll()
              • ✨matchAll() using named groups
              • ✨words in sentence
            • str.random()
            • str.removeWhitespaces()
            • 📘str.replace()
              • 🔰replacer function
              • ✨minus one
            • 💾str.replaceWhitespaces()
            • str.reverse()
            • str.shuffle()
            • 💾str.slice2()
            • 💾str.splice()
            • str.escapeHTML()
            • str.toDatasetPropName()
            • 💾str.words()
            • str.wordCounts()
            • String.fromCharCodes()
          • 👔String extension
            • 💾str.isKeyword
            • 💾str.isReservedWord
            • 💾str.isPunctuator
          • 🔰Unicode
            • 🔰code point
            • 🔰grapheme cluster
            • 🔰code plane
            • 🔰character encoding
              • 🔰UTF-16
                • 🔰code unit
                • 🔰surrogate pair
                • 🔰scalar
        • 🔺Symbol
          • 🔺Symbol.iterator
        • 🔰primitive wrapper
      • 🍄object
        • 🔸property
          • 🚩attribute
            • 🍄property descriptor
            • 💾ownPropertyFlags(obj)
          • 🔸getter/setter
          • 🔸property name
            • ⭐computed property name
          • ⭐shorthand property
          • 🔸internal property
          • 🔰property access
            • 📦property access expression
            • ➕dot notation (.)
              • ⚖️dot notation vs. decimal point
            • ➕bracket notation []
            • ➕optional chaining (?., ?.[])
              • ❓is Optional Chaining Supported?
              • 💾obj.prop(path)
            • ➕optional invocation ?.()
              • is Optional Chaining Supported?
              • obj.prop(path)
            • 🌟chaining rules
              • ✨jane.boyfriend?.money.more
          • 🔰property creation/deletion
            • 📘Object.defineProperty()
            • ➕delete
              • ❗unqualified identifier for delete
          • 🔰property testing
          • 🔰property enumeration
        • 🔰creating objects
          • ✡️object literal
            • ❗object literal is not a block❗️
          • ➕new
            • 🔸new.target
            • ⚖️callable vs. constructable
          • Ⓜ️Object.create()
            • ✨"pure" object
            • ✨guard against accidental modifications
        • 🔰extending objects
          • 📘Object.assign()
            • ⛔️ Object.assign causing TypeError
            • ❗️Object.assign copies with getter/setter
          • inheritance
            • 🔸__proto__
            • class A vs. class A extends Object
          • mixin
            • 💾mergeWithoutOverride()
            • 💾.assignDescriptors()
            • mixin inheritance
            • ✨mixin: HandleEvents
          • 💾 add default properties
          • extending built-in classes
        • 🔰converting objects
          • 🔰serializing objects
          • 🌟object -> primitive conversion
            • 🔘prefer-string
            • 🔘prefer-number
            • 🔘no preference
          • Ⓜ️.toString()
          • Ⓜ️.valueOf()
          • 💾valueToString()
        • Ⓜ️method
          • 💠[[HomeObject]]
          • 🔰polymorphism
        • 🔸prototype
          • 🔰prototype chain
            • 🚧printPrototypeChain()
      • 🍄function
        • 🔰creating functions
        • 🈯function declaration
          • ❗function in block (FiB)
          • ❗function redeclaration
          • 📘function declaration instantiation
        • 🔰function expression
          • ❗read-only identifier
          • 🔰named function expression
          • 🔰as variable
          • 🔰IIFE
        • 🔰arrow function
          • ❗arrow function as method❗️
          • 🔰arrow function as argument
          • ❗arrow function as class field❗️
          • ❗arrow function returning object literal needs (...)❗️
          • 🔰arrow function expression
        • 🔰closure
          • ❗scopes matter with closures
          • 💡private property by closure
          • ✨closure examples
            • ✨closure: to close over or not
            • ✨closure: manage grades
            • ✨closure as object
        • 🌿sorts of function
          • 🔰callback
          • 🔰higher-order function
            • 💾not(f)
            • 💾pipe(f, g, ...)
            • 💾partial(f, a, b ...)
            • 🧚decorator
              • 💾saveCallHistory(f)
              • 💾delay(f, s)
              • 💾benchmark(f)
              • 💾debounce(f, s)
              • 💾throttle(f, s)
              • ⚖️debounce vs. throttle
              • 🧚memoization
                • 🧚memoize by decorator
                  • 💾memoize(f)
                • 🧚memoize by closure
          • 🔰predicate
          • 🔰nested function
          • 🔰recursive function
            • ✨findSolution()
            • 💾deepEqual()
        • 🔰function boundary
        • 🔰function overloading
        • 🔰function forwarding
        • 🔸return value
        • 🔸function name
          • 🔰anonymous function
        • ⚖️parameter vs. argument
        • 🔸argument
          • ❗arguments are passed by value❗️
        • 🔸parameter
          • 🔸default parameter
          • 🔸rest parameters
            • 🔸rest parameters as object
          • 🔸destructured parameter
          • ⚖️simple vs. non-simple parameter
          • ❗deplicate parameters
        • 🔸prototype
        • 🔹constructor
      • 🍄class
        • 🔰initialization
          • 🔹static block
        • 🔸member
          • 🔸class field
          • 🔸private member
          • 🔸static member
            • 🔰init static property
          • private/protected members
          • 🔸getter/setter
          • 🔸method
          • 🔸bound method
        • 🔰creating class
          • 🔰delegation
        • 🔰inheritance
          • 📘super
          • derived class init
          • override constructor
          • override methods
          • override class fields
        • ✨examples
          • ✨Complex
          • ✨TypedMap
          • ✨Bag
      • 📘built-in objects
        • 📘Object
          • 🔸Object.prototype
          • 💾Object extension
            • 💾obj.mergeWith()
        • 📘Function
        • 📘Array
          • 🔸element
            • 🔸element index
              • ❗element index is string❗️
          • 🔸array length
          • 🔸array object property
          • 🍄sparse array
            • 🔰how array methods deal with "holes" ?
          • 🔰array-like
            • 👔Object+arrayLike
          • 🔰creating arrays
            • ✡️array literal
              • 🔰undefined element
          • 🔰accessing elements
          • 🔰iterating elements
          • 📘array methods
            • 📘arr.entries
            • 📘arr.filter()
            • 📘arr.flatMap()
            • 📘arr.reduce()
              • early break reduce()
            • 📘arr.slice()
            • 📘arr.splice()
          • 👔Array extension
            • 💾arr.containsSubarray()
            • 💾arr.copy()
            • 💾arr.isEmpty
            • 💾arr.last
            • 💾arr.none()
            • 💾arr.reversed()
            • 💾arr.shuffle()
            • 💾arr.randomElement
            • 💾arr.removeDuplicates()
            • 💾arr.uniqueMerge()
            • 💾arr.removeUndefined()
            • 💾arr.removeValue()
            • 💾arr.sum(), .average()
            • 💾arr.topN()
            • 💾arr.rank()
            • 💾arr.padEndSpaces()
            • 💾arr.max()
            • 💾arr.isMatrix
            • 💾arr.indexDictionaryForValues()
            • Array extensions (archive)
          • ✨array examples
            • 💾objects to HTML table
          • array & matrix methods
          • static methods
            • 📍Array(n) vs. Array(n).fill()
            • Array.from()
            • 🚧Array.list(n)
          • matrix methods
            • mat.matrixMap()
            • mat.transpose()
            • mat.maxElementInEachColumn()
          • Matrix methods
            • 🌀 Array.matrixFill()
        • 📘Set
          • 👔Set extension
            • 💾set.isEqualTo()
        • 📘Map
          • Don't use object properties
        • 📘RegExp
          • 🚩regex flag
            • 🚩flag /u
            • 🚩flag /d
          • 🔸lastIndex
          • 🔰creating regex
          • 🔰using regex
          • 🔰pattern
            • 🔰special characters
            • 🔰anchor
            • 🔰repeat
              • 🔰greedy vs. lazy
            • 🔰character set
            • 🔰alternation (or)
            • 🔰group
              • 🔰capturing group
                • 🔰named group
            • 🔰lookaround
            • 🔰inline modifier
            • 🔰replace pattern
            • 😀emoji
          • ✨regex examples
            • ✨parse .ini file
            • ✨quick brown fox
            • ✨JS-style numbers
        • 📘Proxy
          • 🔹handler method
          • 📘Reflect
          • ✨Proxy examples
            • ✨identity (proxy)
            • ✨read-only proxy
            • ✨observe()
        • 📘Date
    • 🔰variable
      • 🈯variable declaration
        • 📜var
          • ✅stop using var❗️
          • ❗var is a statement❗️
          • ❗var has no block scope❗️
          • ❗accessing var before declaration gets undefined❗️
          • ❗global var / function is global object property❗️
          • ❗var redeclaration applied even in strict mode❗️
          • ❗var in block can't shadow outer let❗️
          • ❗var can shadow parameter even in strict mode❗️
        • 🈯const
          • ⛔const requires initialization
          • ⛔const can't reassign
          • ⛔no const for classic "for"
        • 🈯let
          • ✅let redeclaration not allowed even in sloppy mode❗️
          • ✅let can't shadow parameter even in sloppy mode❗️
        • 🔰initial value
      • ❗variable redeclaration
        • ❗var redeclaration
        • ❗let redeclaration
      • 🔴accessing variables
        • ⛔temporal dead zone
          • ⛔TDZ
          • ⛔typeof let/const/class in TDZ gets an error❗️
        • ⛔uninitialized variable
        • 🔰LHS reference
        • 🔰RHS reference
        • ⚖️LHS vs. RHS reference
      • ❗variable shadowing
      • ❗can't delete variable/function❗️
    • 🔰module
      • ⭐ES module
        • 🈯import
          • ✨import ES module
          • dynamic import()
        • 🈯export
          • 📘default export
          • 📘named export
      • 🔰CommonJS
        • 📜package.json
      • ⚖️ES vs CommonJS
      • 🔰import.meta
      • 🔰package
      • 🔰bundler
      • 🔰minifier
      • 🔰browser-specific features
      • 🔰module pattern
    • 🔰iteration
      • 👔Iterable+ext
        • 💾range()
        • 💾obj.isIterable
      • 🔰iterable
        • 🔸make-iterator method
        • ❗only-iterate-once iterable
        • 🔰make iterables
        • ✨iterable examples
          • ✨ClosedRange
          • ✨Sequence
      • 🔰iterator
        • 🔸next()
        • 🔸return()
        • ❗iterators only iterate once❗️
        • 🔰iterable iterator
        • 🔰infinite iterator
        • 🔰make iterator iterable
        • 💾IteratorPrototype
        • 💾Iterator
      • 🔰iteration result
      • 📘Generator
        • 🔰generator function
          • 📘function*
          • 📦yield
          • 📘yield*
          • 🔰composition
          • 🔰generator function as ...
        • ✨generator examples
          • 💾*list()
          • 💾*integers()
          • 💾*closedRange()
          • 💾*fibonacci()
          • 💾*zip()
          • 💾*sequence()
          • 💾*interleave()
    • 🔰async code
      • 🔰thread
      • 🔰event loop
      • 🍄Promise
        • 👔custom promises
          • 💾getJSON()
          • 💾Promise.wait()
          • 💾futureValue()
        • 🔰using Promises
        • 🔰error handling
          • ⭐finally()
          • 🔰recoverable errors
        • 🔰chaining Promises
          • 💾Promise.inSeries()
        • 🔰Promises in parallel
      • 🆔async
        • 🔰async function
        • 🔰async method
        • 🔰async arrow function
        • 🔰async IIFE
        • 💾measureTime()
      • ➕await
        • 🔰await promises
          • 🔰await sequentially
          • 🔰await in parallel
        • 🔰await "thenable"
        • 🔰error handling
    • 🔰debugging
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  1. JS
  2. grammar
  3. operator
  4. terms for operator

lvalue

LHS reference of variable/property/element.

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Last updated 2 years ago

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⟩ ⟩ ⟩ ⟩ ⟩ lvalue

(expression)

variable / (object) property / (array) element that appears on the left side of an assignment.

synonyms： "assignment target"

delete expects its operand to be an lvalue, if it is not an lvalue, the operator takes no action and returns true.

lvalue can be used in for-of / for-in loop.

  • LHS reference

  • lvalue can be used in a for-of / for-in loop.

    • ⟩ (for "assignment target")

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JS
statement
expression
operator
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for...in
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