当我使用“和”或“或”时，为什么我的替换在javascript中正常工作，但在我使用“＆”或“/”或“+”时却没有

Question

I have a first name input in a HTML form and sometimes a user will input two first names and I need to strip out the second name and the word or character used to join them. If I use the word "and" or the word "or" my javascript works fine and strips out the second name and the word used to join them. However, if I use an ampersand (&) or a plus sign (+) or a forward slash (/), no matter how I code it, it will only strip out the last character of the second name and not the joining character or any af the second name except the last character.

I have tried using string functions, regular expressions, testing my regular expression at regex.com (they work there and properly select the words and the joining words), a dozen different variations of my regular expression that all work properly at regex, com to select the text I want removed, but none of this works in my actual form.

For instance if I input: "Bob and Dave" I get "Bob" - Correct "Bob or Dave" I get "Bob" - Correct

But if I input: "Bob & Dave" I get "Bob & Dav" - Incorrect "Bob + Dave" I get "Bob + Dav" - Incorrect "Bob / Dave" I get "Bob " - Incorrect but Acceptable "Bob, Dave" I get "Bob, Dav" - Incorrect

This is some of the code I have used, several different approaches have worked for the first two, nothing has worked for the last four.

Works for "Bob and Dave":

function noExtraNames() {
var pattern=document.forms[0].first_name.value;
var z = pattern.search(/(\s)*\w+/gi)
var x = pattern.search("AND", z+1)
if (z < x) {
    alert('Please only enter ONLY ONE FIRST NAME')
    document.forms[0].first_name.focus();
    return document.forms[0].first_name.value=pattern.replace(/\s(AND)*\w+/gi, "");
}
}

Works for "Bob or Dave":

function noExtraNames() {
var pattern=document.forms[0].first_name.value;
var z = pattern.search(/\s(OR)*\w+/gi)
var x = pattern.search("OR", z+1)
if (z < x) {
    alert('Please only enter ONLY ONE FIRST NAME')
    document.forms[0].first_name.focus();
    return document.forms[0].first_name.value=pattern.replace(/\s(or)*\w+/gi, "");
}
}

This also worked for "Bob and Dave" and changing the corresponding word "and" for "or", worked for "Bob or Dave":

function noExtraNames() {
var pattern=document.forms[0].first_name.value;
var z = pattern.search("and")
var x = pattern.search("and")
if (z < x) {
    alert('Please only enter ONLY ONE FIRST NAME')
    document.forms[0].first_name.focus();
    return document.forms[0].first_name.value=pattern.slice(0, z);
}
}

However, this worked for the incorrect but acceptable "Bob, Dave", but did not work for "Bob & Dave" or "Bob / Dave", when the appropriate characters were substituted:

function noExtraNames() {
var pattern=document.forms[0].first_name.value;
var z = pattern.search(/(,\s+)/gi);
var x = pattern.search((/(,\s+)/gi), z-1);
if (z < x) {
    alert('Please only enter ONLY ONE FIRST NAME');
    document.forms[0].first_name.focus();
    return document.forms[0].first_name.value=pattern.replace(/(,\s+)/gi);
}
}

And this yielded the same incorrect result with "&" and "/":

function noExtraNames() {
var pattern=document.forms[0].first_name.value;
var z = pattern.search(/(\s&)/gi);
var x = pattern.search(/(\s&\s.[a-z].+)/gi, z-1);
if (x < z) {
    alert('Please only enter ONLY ONE FIRST NAME');
    document.forms[0].first_name.focus();
    return document.forms[0].first_name.value=pattern.replace(/(\s&\s.[a-z].+)/gi, "");
}
}

The regular expressions all worked to select the proper text at regex.com, but never work in my form and I am almost out of hair to pull in frustration.

Why is this happening and more importantly how can I fix it. I have tried several other solutions I found on this site such as:

function noExtraNames() {
var pattern=document.forms[0].first_name.value;
var z = pattern.search(/(,\s+)/gi);
var x = pattern.search((/(,\s+)/gi), z-1);
if (x < z) {
    alert('Please only enter ONLY ONE FIRST NAME');
    document.forms[0].first_name.focus();
    var s = document.forms[0].first_name.value;
    var n = s.indexOf('&');
    s = s.substring(0, n != -1 & n : s.length);
    return document.forms[0].first_name.value = s;
}
}

All for no joy.

The expected output is: Bob The actual output is: Bob & Dav

Answer 1

It seems like this would be better handled by splitting on the regex and returning the first item. This pattern should take care of the cases mentioned in your post:

var pattern = /(\s*[\+|&|\,|\/]\s*|\s+(and|or)\s+)/i;

then splitting and always returning the first element.

 function noExtraNames(name) { var pattern = /(\\s*[\\+|&|\\,|\\/]\\s*|\\s+(and|or)\\s+)/i; var items = name.split(pattern); if (items.length > 1) { console.log('Please only enter ONLY ONE FIRST NAME'); return items[0]; } return name; } let tests = [ 'Bob', 'Billy Bob', 'Bob and Dave', 'Bob + Dave', 'Bob & Dave', 'Bob / Dave', 'Bob, Dave', 'Igor', 'Andy', 'Bob+Dave', ]; for (let test of tests) { console.log(test, '===> ', noExtraNames(test)); } 

Answer 2

const pattern = /(.*(?=(\s+(and|or)\s+)|(\s*[\&\+,\/\\])))|.*/i;
const patternMatch = str.match(pattern);
if (patternMatch[1]) {
  alert('Please only enter ONLY ONE FIRST NAME');
}
const replaceValue = patternMatch[0].trim();
document.forms[0].first_name.value = replaceValue;

I guess that's what you need.