“ i” 是保留变量吗？似乎是一个不太可能的问题。但是，当我在计算机上运行以下简单代码并将FOR循环中使用的迭代变量设置为“ i” 后，在第一次执行循环“ i” 返回为 63 。
当“ i” 更改为 z，omega或其他变量名称时，循环将按预期运行。我想念什么吗？我的计算机有问题吗？
/*
This javascript code demonstrates a simple encode/decode of a string using a hash of possible values
stored in a JSON object.
*/
objPossibleCharacters = {
"Z" : "c", "Y" : "i", "X" : "P", "W" : "O",
"V" : "b", "U" : "5", "T" : "V", "S" : "a",
"R" : "4", "Q" : "Z", "P" : "U", "O" : "h",
"N" : "d", "M" : "R", "L" : "3", "K" : "N",
"J" : "E", "I" : "w", "H" : "D", "G" : "2",
"F" : "e", "E" : "v", "D" : "q", "C" : "j",
"B" : "Q", "A" : "1", "0" : "G", "1" : "f",
"2" : "C", "3" : "F", "4" : "o", "5" : "M",
"6" : "0", "7" : "r", "8" : "L", "9" : "H",
"a" : "g", "b" : "6", "c" : "s", "d" : "m",
"e" : "S", "f" : "7", "g" : "x", "h" : "p",
"i" : "X", "j" : "B", "k" : "8", "l" : "I",
"m" : "y", "n" : "T", "o" : "k", "p" : "J",
"q" : "W", "r" : "z", "s" : "K", "t" : "l",
"u" : "t", "v" : "9", "w" : "A", "x" : "Y",
"y" : "u", "z" : "n", "!" : "%", "?" : "~",
"," : "*", "." : "$", " " : "|"
};
function encodeString( str ){
encodedStr = "";
for (i=0; i < str.length; i++){
encodedStr += objPossibleCharacters[str.charAt(i)];
}
//console.log( encodedStr );
return encodedStr;
}
function decodedString( str ){
decodedStr = "";
value = "";
for ( i=0; i < str.length; i++ ){
value = str.charAt(i);
decodedStr += getKeyByValue( value );
}
//console.log( decodedStr );
return decodedStr;
}
function getKeyByValue( value ){
for ( key in objPossibleCharacters ){
if ( objPossibleCharacters.hasOwnProperty( key ) ){
if ( objPossibleCharacters[key] === value ) return key;
}
}
}
var strArray = [
'Sea shells, sea shells. She sells sea shells by the sea shore.',
'Thank you for coming today. I hope you found this session enlightening and useful.',
'Elvis has left the building. You do not need to go home, but you cannot stay here. Get out!' ];
strArrayLength = strArray.length;
// This issue is in the following FOR LOOP
// Change var x = 0 to var i = 0
var x = 0;
for (x=0; x<strArrayLength; ++x){
str = strArray[x];
encodedOutput = encodeString( str );
decodedOutput = decodedString( encodedOutput );
console.log( "" );
console.log( "Original string: " +str );
console.log( "Encoded string: " +encodedOutput );
console.log( "Decoded string: " +decodedOutput );
console.log( strArrayLength +" - "+ x );
console.log( "" );
}
将 i 用作变量时，我只会得到以下输出：
Original string: Sea shells, sea shells. She sells sea shells by the sea shore.
Encoded string: aSg|KpSIIK*|KSg|KpSIIK$||apS|KSIIK|KSg|KpSIIK|6u|lpS|KSg|KpkzS$
Decoded string: Sea shells, sea shells. She sells sea shells by the sea shore.
3 - 63
使用其他变量名称时，将得到以下输出：
Original string: Sea shells, sea shells. She sells sea shells by the sea shore.
Encoded string: aSg|KpSIIK*|KSg|KpSIIK$||apS|KSIIK|KSg|KpSIIK|6u|lpS|KSg|KpkzS$
Decoded string: Sea shells, sea shells. She sells sea shells by the sea shore.
3 - 0
Original string: Thank you for coming today. I hope you found this session enlightening and useful.
Encoded string: VpgT8|ukt|7kz|skyXTx|lkmgu$||w|pkJS|ukt|7ktTm|lpXK|KSKKXkT|STIXxplSTXTx|gTm|tKS7tI$
Decoded string: Thank you for coming today. I hope you found this session enlightening and useful.
3 - 1
Original string: Elvis has left the building. You do not need to go home, but you cannot stay here. Get out!
Encoded string: vI9XK|pgK|IS7l|lpS|6tXImXTx$||ikt|mk|Tkl|TSSm|lk|xk|pkyS*|6tl|ukt|sgTTkl|Klgu|pSzS$||2Sl|ktl%
Decoded string: Elvis has left the building. You do not need to go home, but you cannot stay here. Get out!
3 - 2
答案 0 :(得分：2)
您的所有函数均未正确声明i变量。由于var i = 0得到hoisted，因此该变量将由您的所有函数共享。
例如：
function encodeString( str ){
encodedStr = "";
for (i=0; i < str.length; i++){ ... }
}
正确的声明：
function encodeString( str ){
let encodedStr = "";
for (let i=0; i < str.length; i++){ ... }
}
您正在使用的其他变量也是如此。