Javascript: GUID: RegEx: string to GUID

November 23, 2021

I have a textbox that a user can paste into using Ctrl+V. I would like to restrict the textbox to accept just GUIDs. I tried to write a small function that would format an input string to a GUID based on RegEx, but I can’t seem to be able to do it. I tried following the below post:
Javascript string to Guid

function stringToGUID()
{
    var strInput = 'b6b954d9cbac4b18b0d5a0f725695f1ca98d64e456f76';
    var strOutput = strInput.replace(/([0-f]{8})([0-f]{4})([0-f]{4})([0-f]{4})([0-f]{12})/,"$1-$2-$3-$4-$5");
    console.log(strOutput );
    //from my understanding, the input string could be any sequence of 0-9 or a-f of any length and a valid giud patterened string would be the result in the above code. This doesn't seem to be the case;
    //I would like to extract first 32 characters; how do I do that?

}

>Solution :

I suggest that you remove the dashes, truncate to 32 characters, and then test if the remaining characters are valid before inserting the dashes:

function stringToGUID()
{
    var input = 'b6b954d9cbac4b18b0d5a0f725695f1ca98d64e456f76';
    let g = input.replace("-", "");
    g = g.substring(0, 32);
    if (/^[0-9A-F]{32}$/i.test(g)) {
        g = g.replace(/(.{8})(.{4})(.{4})(.{4})(.{12})/, "$1-$2-$3-$4-$5");
    }
    console.log(g);
}

stringToGUID();

(The i at the end of the regex makes it case-insensitive.)