I need to replace first and last character in random string. Why this code doesn't work?
function symbExchange(line) {
var tmp = line[0];
var str = line.replace(line[0], line[line.length-1]);
var str2 = str.replace(str[str.length-1], tmp);
return str2;
}
That's because the replace function returns a new string with some or all matches of a pattern replaced by a replacement.
If you need to swap characters, you can use a regex in your case (but this is not the best implementation):
function symbExchange(line) {
var tmp = line[0];
var str = line.replace(new RegExp('^' + line[0]), line[line.length-1]);
var str2 = str.replace(new RegExp(str[str.length-1] + '$'), tmp);
return str2;
}
It does not work because replace function will replace the first occurrence
try this :
function symbExchange(line) {
var first = line[0];
var last = line[line.length-1];
line[0] = last;
line[line.length-1] = first
return str2;
}
This line replaces first occurence of character that is same as last character. Not the last character itself.
var str2 = str.replace(str[str.length-1], tmp);
possible solution is not to use replace function:
function symbExchange(line) {
var startCh = line[0];
var endCh = line[line.length-1];
var str = line;
str[0] = endCh;
str[str.length-1] = startCh;
return str;
}
String.Replace when used with a string argument will only replace the first occurrence of that string. You either need to use regex as an argument, or do a split 'n' join. Which one is better /faster will depend on the length of your string and number of occurrences to replace.
var src = "helloworldhello";
var dest = src.replace( /hello/g , "goodbye");
console.log(dest);
or
var src = "helloworldhello";
var dest = src.split("hello").join("goodbye");
Use swapping characters after converting string to array and then to string
function symbExchange(line) {
line = line.split("");
temp=line[0]
line[0]=line[line.length-1]
line[line.length-1]=temp
return line.join("")
}
