I want to delete the first character of a string, if the first character is a 0. The 0 can be there more than once.

Is there a simple function that checks the first character and deletes it if it is 0?

Right now, I'm trying it with 开发者_如何学Cthe JS slice() function but it is very awkward.

You can remove the first character of a string using substring:

var s1 = "foobar";
var s2 = s1.substring(1);
alert(s2); // shows "oobar"

To remove all 0's at the start of the string:

var s = "0000test";
while(s.charAt(0) === '0')
{
 s = s.substring(1);
}

Very readable code is to use .substring() with a start set to index of the second character (1) (first character has index 0). Second parameter of the .substring() method is actually optional, so you don't even need to call .length()...

TL;DR : Remove first character from the string:

str = str.substring(1);

...yes it is that simple...

Removing some particular character(s):

As @Shaded suggested, just loop this while first character of your string is the "unwanted" character...

var yourString = "0000test";
var unwantedCharacter = "0";
//there is really no need for === check, since we use String's charAt()
while( yourString.charAt(0) == unwantedCharacter ) yourString = yourString.substring(1);
//yourString now contains "test"

.slice() vs .substring() vs .substr()

EDIT: substr() is not standardized and should not be used for new JS codes, you may be inclined to use it because of the naming similarity with other languages, e.g. PHP, but even in PHP you should probably use mb_substr() to be safe in modern world :)

Quote from (and more on that in) What is the difference between String.slice and String.substring?

He also points out that if the parameters to slice are negative, they reference the string from the end. Substring and substr doesn´t.

Use .charAt() and .slice().

Example: http://jsfiddle.net/kCpNQ/

var myString = "0String";

if( myString.charAt( 0 ) === '0' )
    myString = myString.slice( 1 );

If there could be several 0 characters at the beginning, you can change the if() to a while().

Example: http://jsfiddle.net/kCpNQ/1/

var myString = "0000String";

while( myString.charAt( 0 ) === '0' )
    myString = myString.slice( 1 );

The easiest way to strip all leading 0s is:

var s = "00test";
s = s.replace(/^0+/, "");

If just stripping a single leading 0 character, as the question implies, you could use

s = s.replace(/^0/, "");

You can do it with substring method:

let a = "My test string";

a = a.substring(1);

console.log(a); // y test string

Did you try the substring function?

string = string.indexOf(0) == '0' ? string.substring(1) : string;

Here's a reference - https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/String/substring

And you can always do this for multiple 0s:

while(string.indexOf(0) == '0')
{
    string = string.substring(1);
}

One simple solution is to use the Javascript slice() method, and pass 1 as a parameter

let str = "khattak01"
let resStr = str.slice(1)
console.log(resStr)

Result : hattak01

var s = "0test";
if(s.substr(0,1) == "0") {
    s = s.substr(1);
}

For all 0s: http://jsfiddle.net/An4MY/

String.prototype.ltrim0 = function() {
 return this.replace(/^[0]+/,"");
}
var s = "0000test".ltrim0();

const string = '0My string';
const result = string.substring(1);
console.log(result);

You can use the substring() javascript function.

//---- remove first and last char of str    
str = str.substring(1,((keyw.length)-1));

//---- remove only first char    
str = str.substring(1,(keyw.length));

//---- remove only last char    
str = str.substring(0,(keyw.length));

try

s.replace(/^0/,'')

console.log("0string  =>", "0string".replace(/^0/,'') );
console.log("00string =>", "00string".replace(/^0/,'') );
console.log("string00 =>", "string00".replace(/^0/,'') );

Here's one that doesn't assume the input is a string, uses substring, and comes with a couple of unit tests:

var cutOutZero = function(value) {
    if (value.length && value.length > 0 && value[0] === '0') {
        return value.substring(1);
    }

    return value;
};

http://jsfiddle.net/TRU66/1/

String.prototype.trimStartWhile = function(predicate) {
    if (typeof predicate !== "function") {
    	return this;
    }
    let len = this.length;
    if (len === 0) {
        return this;
    }
    let s = this, i = 0;
    while (i < len && predicate(s[i])) {
    	i++;
    }
    return s.substr(i)
}

let str = "0000000000ABC",
    r = str.trimStartWhile(c => c === '0');
    
console.log(r);

Another alternative to get the first character after deleting it:

// Example string
let string = 'Example';

// Getting the first character and updtated string
[character, string] = [string[0], string.substr(1)];

console.log(character);
// 'E'

console.log(string);
// 'xample'

From the Javascript implementation of trim() > that removes and leading or ending spaces from strings. Here is an altered implementation of the answer for this question.

var str = "0000one two three0000"; //TEST  
str = str.replace(/^\s+|\s+$/g,'0'); //ANSWER

Original implementation for this on JS

string.trim():
if (!String.prototype.trim) {
 String.prototype.trim = function() {
  return this.replace(/^\s+|\s+$/g,'');
 }
}

Another alternative answer

str.replace(/^0+/, '')

var test = '0test';
test = test.replace(/0(.*)/, '$1');