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-scope-related 1. function func () { if (1==1) { var v= 123; } Console.log (v); } Func () A. error (java,c#) B. 123 (python, pair) c.undefined = "javascript/python is scoped with function, non-parenthesis is scope =" java,c# The brackets are scoped 2. XO = ' root1 '; function func () { var xo = ' Root2 '; function inner () { console.log (xo); } Inner

, each function acts as a scope and variables in the internal scope cannot be accessed externally. Function Main () {var innerValue = 'seven';} Main (); console. log (innerValue); // error: Uncaught ReferenceError: innerValue is not defined Iii. JavaScript scope chain Since each function in JavaScript acts as a scope, if a function is nested, a scope chain will appear. xo = 'alex';function Func(){var xo = "

outer layer of the loop, and if it does not exist, the exception.Remember that all scopes exist when the function is created and not executed.(1) "No block-level scope in JavaScript"function Main () { if (1==1) { var name = ' seven '; } Console.log (name);} Output: SevenAdd: The title adds double quotes because the LET keyword is introduced in JavaScript6 to specify that the variable belongs to a block-level scope.(2) JavaScript takes function scopeIn JavaScript each function ac

internal scope cannot be accessed externally. 123456789 functionMain(){varinnerValue =‘seven‘;} Main();console.log(innerValue);// 报错：Uncaught ReferenceError: innerValue is not defined Third, the scope chain of JavaScriptBecause each function in JavaScript acts as a scope, the scope chain appears if function nesting functions occur. 1234567891011 xo =‘alex‘;functionFunc(){varxo ="seven";function inner()

JavaScript One, no block-level scope in JavaScript A brace is scoped to a block-level scope, and block-level scopes exist in Java and C # function Main () { if (1==1) { var name = ' seven '; } Console.log (name);} Output: SevenSecond, JavaScript uses function scope In JavaScript each function acts as a scope, outside of which the variables in the internal scope cannot be accessed function Main () { var innervalue = ' Seven ';} Main (); Console.log (

internal scope cannot be accessed externally.function Main () { var innervalue = ' Seven ';} Main (); Console.log (Innervalue); Error: Uncaught referenceerror:innervalue is not definedThird, the scope chain of JavaScriptBecause each function in JavaScript acts as a scope, the scope chain appears if function nesting functions occur. 1234567891011 xo =‘alex‘;functionFunc(){varxo ="seven";functioninner(){varxo =‘alvin‘;console.log(

(){varinnerValue =‘seven‘;} Main();console.log(innerValue);// 报错：Uncaught ReferenceError: innerValue is not defined Third, the scope chain of JavaScriptBecause each function in JavaScript acts as a scope, the scope chain appears if function nesting functions occur. 1234567891011 xo =‘alex‘;functionFunc(){varxo ="seven";function inner(){varxo =‘alvin‘;console.log(xo);}inner();}Fun