Replace character in array - JavaScript

Question

I am trying to replace the 8th character in each element of an array. I know JavaScript does not have a built-in function to replace string characters. I was able to find to potentially helpful code on this site. They accept strings as parameters, but when I pass in a array such as cookies[0], it does not change anything in the string. Why is that? Is there a way I can get this to work? Thanks in advance for any help.

var cookies = ["cartItem1", "cartItem2", "cartItem3", "cartItem4"];

function setCharAt(str,index,chr) {
    if(index > str.length-1) return str;
    return str.substr(0,index) + chr + str.substr(index+1);
}

function delCookie(){
    cookies.splice(0,1);
    setCharAt(cookies[0], 8, "Z");

}

delCookie();

I also tried it this way:

var cookies = ["cartItem1", "cartItem2", "cartItem3", "cartItem4"];


String.prototype.replaceAt=function(index, character) {
    return this.substr(0, index) + character + this.substr(index+character.length);
};

function delCookie2(){
    cookies.splice(0,1);
    cookies[0].replaceAt(8, "Z");
}

delCookie2();

Additional information about the answers given: In JavaScript, strings are immutable, which means that they cannot be changed -- ever. They can only be replaced. — Jeremy J Starcher
– Jeremy J Starcher, Commented May 3, 2014 at 13:39

bbuecherl · Accepted Answer · 2014-05-03 13:35:05Z

2

Both your methods (setCharAt and replaceAt) are returning the result, which means you have to set it:

function delCookie() {
   cookies.splice(0,1);
   cookies[0] = cookies[0].replaceAt(8, "Z"); 
   //or
   // cookies[0] = setCharAt(cookies[0], 8, "Z");
}

answered May 3, 2014 at 13:35

bbuecherl

1,61913 silver badges20 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

thorsday · Accepted Answer · 2014-05-03 13:36:58Z

0

The "setCharAt" function doesn't actually alter the string passed in - it returns a new string with the appropriate character changed. In order to get the behavior you want, you'll have to replace the old string in your array with the new one.

answered May 3, 2014 at 13:36

thorsday

3642 silver badges7 bronze badges

Collectives™ on Stack Overflow

Replace character in array - JavaScript

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related