使用javascript只显示银行账户的最后4位数字

Question

I need help with Javascript. I need to replace however many characters there are previous to the last 4 digits of a text field that contains bank account number. I have searched through the net on this, but cannot find one code that works. I did find a code here on stackoverflow, which was regarding credit card,

new String('x', creditCard.Length - 4) + creditCard.Substring(creditCard.Length - 4);

I just replaced the creditCard with accounNumObject:

var accounNumObject = document.getElementById("bankAcctNum")

The input is pretty simple.

<cfinput type="text" name="bankAcctNum" id="bankAcctNum" maxlength="25" size="25" value="#value#" onblur="hideAccountNum();">

Can anyone help please?

Answer 1

To replace a string with x except for the last four characters in JavaScript, you could use (assuming str holds the string)...

var trailingCharsIntactCount = 4;

str = new Array(str.length - trailingCharsIntactCount + 1).join('x')
       + str.slice(-trailingCharsIntactCount);

jsFiddle .

You could also use a regular expression...

str = str.replace(/.(?=.{4})/g, 'x');

If you want to add the 4 from a variable, construct the regex with the RegExp constructor.

jsFiddle .

If you're fortunate enough to have the support, also...

const trailingCharsIntactCount = 4;

str = 'x'.repeat(str.length - trailingCharsIntactCount)
        + str.slice(-trailingCharsIntactCount);

Polyfill for String.prototype.repeat() is available .

Answer 2

Here is a fiddle showing what you're asking for:

http://jsfiddle.net/eGFqM/1/

<input id='account' value='abcdefghijklmnop'/>
<br/>
<input id='account_changed'/>

var account = document.getElementById('account');
var changed = document.getElementById('account_changed');

changed.value = new Array(account.value.length-3).join('x') + 
    account.value.substr(account.value.length-4, 4);

Edit: Updated fiddle to correct off by one problem pointed out by alex

Answer 3

Agreed with all above solutions.I just had one another approach.

 const maskAccountId = (accountId) => { if (accountId) { /** Condition will only executes if accountId is *not* undefined, null, empty, false or 0*/ const accountIdlength = accountId.length; const maskedLength = accountIdlength - 4; /** Modify the length as per your wish */ let newString = accountId; for (let i = 0; i < accountIdlength; i++) { if (i < maskedLength) { newString = newString.replace(accountId[i], '*'); } } return newString; } else return /**Will handle if no string is passed */ } console.log(maskAccountId('egrgrgry565yffvfdfdfdfdfgrtrt4t4'));