这个符号在JavaScript中意味着什么？

Question

这是什么？

这是一系列关于JavaScript语法的问题。这也是社区Wiki，所以每个人都被邀请参与维护此列表。

为什么会这样？

Stack Overflow不允许搜索特定字符。因此，在搜索运算符和其他语法标记时，很难找到许多关于运算符和其他语法标记的问题。这也使得关闭重复更加困难。以下列表是为了解决这个问题。

主要思想是在Stack Overflow上链接现有问题，因此我们更容易引用它们，而不是复制ECMAScript规范中的内容。

此外，这是PHP符号引用的公然副本。我们需要一个JS。

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请帮忙。编辑并添加指向其他运算符/语法参考的链接，或者如果您无法在特定语法上找到好的问题/答案，请添加此问题的答案并将其链接

Answer 1

MDN reference on operators

列表

==，===平等操作员

• Which equals operator (== vs ===) should be used in JavaScript comparisons?
• How does JS type coercion work?
• In Javascript, <int-value> == "<int-value>" evaluates to true. Why is it so?
• [] == ![] evaluates to true
• Why does "undefined equals false" return false?
• Why does !new Boolean(false) equals false in JavaScript?
• Javascript 0 == '0'. Explain this example
• Why false == "false" is false?

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!=，!==不平等运算符

• != vs. !==
• Javascript operator !==

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&&，||，!逻辑运算符

• Logical operators in JavaScript — how do you use them?
• Logical operator || in javascript, 0 stands for Boolean false?
• What does "var FOO = FOO || {}" (assign a variable or an empty object to that variable) mean in Javascript?，JavaScript OR (||) variable assignment explanation，What does the construct x = x || y mean?
• Javascript AND operator within assignment
• What is "x && foo()"?（还有here和here）
• What is the !! (not not) operator in JavaScript?
• What is an exclamation point in JavaScript?

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()分组运算符

• MDN: Grouping operator

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,逗号运算符

• What does a comma do in JavaScript expressions?
• Comma operator returns first value instead of second in argument list?
• When is the comma operator useful?

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?…:条件（三元）运算符

• Question mark and colon in JavaScript
• Operator precedence with Javascript Ternary operator
• How do you use the ? : (conditional) operator in JavaScript?

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|，&，^，~ Bitwise OR, AND, XOR & NOT operators

• What do these JavaScript bitwise operators do?
• How to: The ~ operator?
• Is there a & logical operator in Javascript
• What does the "|" (single pipe) do in JavaScript?
• What does the operator |= do in JavaScript?
• Javascript, What does the ^ (caret) operator do?
• Using bitwise OR 0 to floor a number，How does x|0 floor the number in JavaScript?
• Why does ~1 equal -2?
• What does ~~ ("double tilde") do in Javascript?
• How does !!~ (not not tilde/bang bang tilde) alter the result of a 'contains/included' Array method call?（还有here和here）

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<<，>>，>>> Bit shift operators

• What do these JavaScript bitwise operators do?
• What is the JavaScript >>> operator and how do you use it?

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+，-运营商

• What does = +_ mean in JavaScript，Single plus operator in javascript
• What's the significant use of unary plus and minus operators?
• Why is [1,2] + [3,4] = "1,23,4" in JavaScript?

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++，--前/后递增/递减运算符

• ++someVariable vs someVariable++ in Javascript

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void运营商

• What does `void 0` mean?

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var x = function() vs function x()函数声明语法

• var functionName = function() {} vs function functionName() {}

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=>箭头函数表达式语法

• What's the meaning of "=>" (an arrow formed from equals & greater than) in JavaScript?

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(function(){...})() IIFE （立即调用函数表达式）

• What is the purpose?，How is it called?
• Why does (function(){…})(); work but function(){…}(); doesn't?
• (function(){…})(); vs (function(){…}());
• shorter alternatives：
  • !function(){…}(); - What does the exclamation mark do before the function?
  • +function(){…}(); - JavaScript plus sign in front of function name
  • !function(){ }() vs (function(){ })()，! vs leading semicolon
• (function(window, undefined){…}(window));

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someFunction()() 返回其他功能的函数

• Two sets of parentheses after function call

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[]，Array()数组表示法

• What’s the difference between "Array()" and "[]" while declaring a JavaScript array?
• What is array literal notation in javascript and when should you use it?

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/.../ - 正则表达式文字

• Meaning of javascript text between two slashes

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正则表达式中的

$替换模式：$$，$&，$`，$'，$n

• JavaScript replace() method dollar signs

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{key: value}对象文字语法：

• What do curly braces in JavaScript mean?
• Javascript object literal: what exactly is {a, b, c}?
• What do square brackets around a property name in an object literal mean?

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解构：

• 函数参数：Where can I get info on the object parameter syntax for javascript functions?
• 数组：Multiple assignment in javascript? What does [a,b,c] = [1, 2, 3]; mean?
• of objects / imports：Javascript object bracket notation ({ Navigation } =) on left side of assign

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模板文字：

• What does this `…${…}…` code from the node docs mean?
• Usage of the backtick character (`) in JavaScript?

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function*，yield，yield*生成器功能：

• What is "function*" in JavaScript?
• What's the yield keyword in JavaScript?
• Delegated yield (yield star, yield *) in generator functions

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var，let，const声明变量：

• What's the difference between using "let" and "var"?
• Are there constants in JavaScript?
• What is the temporal dead zone?

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this关键字：

• How does the "this" keyword work?

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::绑定运营商：

• JavaScript double colon (bind operator)

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new运营商

• What is the 'new' keyword in JavaScript?
• What is "new.target"?

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delete运营商

• What is the purpose of the delete operator in Javascript?

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label:标签

• What does the JavaScript syntax foo: mean?
• What does ':' (colon) do in JavaScript?

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+=运营商

• How does += (plus equal) work?

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...iter - 传播语法/ Rest参数

• (...args) => {} - What is the meaning of "...args" (three dots) in a function definition?
• [...iter] - javascript es6 array feature [...data, 0] "spread operator"
• {...props} - Javascript Property with three dots (...)

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|>运营商

• What does the "|>" operator do in Javascript?