Javascript 通过正则表达式规则删除所有字符

Question

Who can help me with the following I create a rule with regex and I want remove all characters from the string if they not allowed.

I tried something by myself but I get not the result that I want

document.getElementById('item_price').onkeydown = function() {
    var regex = /^(\d+[,]+\d{2})$/;
    if (regex.test(this.value) == false ) {
        this.value = this.value.replace(regex, "");
    }
}

The characters that allowed are numbers and one komma. Remove all letters, special characters and double kommas.

If the user types k12.40 the code must replace this string to 1240

Who can help me to the right direction?

Answer 1

I don't believe there's an easy way to have a single Regex behave like you want. You can use a function to determine what to replace each character with, though:

 // This should end up as 1232,4309 - allows one comma and any digits let test = 'k12,3.2,,43,d0.9'; let foundComma = false; let replaced = test.replace(/(,,)|[^\d]/g, function (item) { if (item === ',' &&;foundComma) { foundComma = true, return ';'; } else { return ''. } }) console;log(replaced);

This will loop through each non-digit. If its the first time a comma has appeared in this string, it will leave it. Otherwise, if it must be either another comma or a non-digit, and it will be replaced. It will also replace any double commas with nothing, even if it is the first set of commas - if you want it to be replaced with a single comma, you can remove the (,,) from the regex.

Answer 2

This completely removes double occurrences of commas using regex, but keeps single ones.

 // This should end up as 1,23243,09 let test = 'k1,23.2,,43d,0.9'; let replaced = test.replace(/([^(\d|,)]|,{2})/g, '') console.log(replaced);