在 JavaScript 中修剪字符串

Question

如何从字符串的开头和结尾删除所有空格？

Answer 1

["

All browsers since IE9+ have trim()<\/code><\/a> method for strings:<\/i>

" \n test \n ".trim(); // returns "test" here

Answer 2

The trim from jQuery is convenient if you are already using that framework.

$.trim('  your string   ');

I tend to use jQuery often, so trimming strings with it is natural for me. But it's possible that there is backlash against jQuery out there? :)

Answer 3

Although there are a bunch of correct answers above, it should be noted that the String object in JavaScript has a native .trim() method as of ECMAScript 5 . Thus ideally any attempt to prototype the trim method should really check to see if it already exists first.

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

Added natively in: JavaScript 1.8.1 / ECMAScript 5

Thus supported in:

Firefox: 3.5+

Safari: 5+

Internet Explorer: IE9+ (in Standards mode only!) http://blogs.msdn.com/b/ie/archive/2010/06/25/enhanced-scripting-in-ie9-ecmascript-5-support-and-more.aspx

Chrome: 5+

Opera: 10.5+

ECMAScript 5 Support Table: http://kangax.github.com/es5-compat-table/

Answer 4

There are a lot of implementations that can be used. The most obvious seems to be something like this:

String.prototype.trim = function() {
    return this.replace(/^\s+|\s+$/g, "");
};

" foo bar ".trim();  // "foo bar"

Answer 5

Simple version here What is a general function for JavaScript trim?

function trim(str) {
        return str.replace(/^\s+|\s+$/g,"");
}

Answer 6

我知道三年前就有人问过这个问题。现在， String.trim()是在 JavaScript 中原生添加的。例如，您可以直接修剪如下，

document.getElementById("id").value.trim();

Answer 7

If you are using jQuery, use the jQuery.trim() function. For example:

if( jQuery.trim(StringVariable) == '')

Answer 8

Flagrant Badassery has 11 different trims with benchmark information:

http://blog.stevenlevithan.com/archives/faster-trim-javascript

Non-surprisingly regexp-based are slower than traditional loop.

---

Here is my personal one. This code is old! I wrote it for JavaScript1.1 and Netscape 3 and it has been only slightly updated since. (Original used String.charAt)

/**
 *  Trim string. Actually trims all control characters.
 *  Ignores fancy Unicode spaces. Forces to string.
 */
function trim(str) {
    str = str.toString();
    var begin = 0;
    var end = str.length - 1;
    while (begin <= end && str.charCodeAt(begin) < 33) { ++begin; }
    while (end > begin && str.charCodeAt(end) < 33) { --end; }
    return str.substr(begin, end - begin + 1);
}

Answer 9

Use the Native JavaScript Methods: String.trimLeft() , String.trimRight() , and String.trim() .

String.trim() is supported in IE9+ and all other major browsers :

'  Hello  '.trim()  //-> 'Hello'

String.trimLeft() and String.trimRight() are non-standard, but are supported in all major browsers except IE

'  Hello  '.trimLeft()   //-> 'Hello  '
'  Hello  '.trimRight()  //-> '  Hello'

IE support is easy with a polyfill however:

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

Answer 10

String.prototype.trim = String.prototype.trim || function () {
    return this.replace(/^\s+|\s+$/g, "");
};

String.prototype.trimLeft = String.prototype.trimLeft || function () {
    return this.replace(/^\s+/, "");
};

String.prototype.trimRight = String.prototype.trimRight || function () {
    return this.replace(/\s+$/, "");
};

String.prototype.trimFull = String.prototype.trimFull || function () {
    return this.replace(/(?:(?:^|\n)\s+|\s+(?:$|\n))/g, "").replace(/\s+/g, " ");
};

Shamelessly stolen from Matt duereg .

Answer 11

Now days you can use string.trim() that is native Javascript implementation

var orig = "   foo  ";
console.log(orig.trim());//foo

See also

• trimLeft()
• trimRight()

Answer 12

Trim code from angular js project

var trim = (function() {

  // if a reference is a `String`.
  function isString(value){
       return typeof value == 'string';
  } 

  // native trim is way faster: http://jsperf.com/angular-trim-test
  // but IE doesn't have it... :-(
  // TODO: we should move this into IE/ES5 polyfill

  if (!String.prototype.trim) {
    return function(value) {
      return isString(value) ? 
         value.replace(/^\s*/, '').replace(/\s*$/, '') : value;
    };
  }

  return function(value) {
    return isString(value) ? value.trim() : value;
  };

})();

and call it as trim(" hello ")

Answer 13

["

use simply code<\/i>

var str = "       Hello World!        ";
alert(str.trim());

Answer 14

You can just declare your variable as string and use its trim function:

var str = new String('my string'); 
str= str.trim();

Answer 15

Here's a very simple way:

function removeSpaces(string){
return string.split(' ').join('');
}

Answer 16

Today, pretty much every browser supports String.prototype.trim() .

You use it like this :

var origStr = '   foo  ';
var newStr = origStr.trim(); // Value of newStr becomes 'foo'

In case you still might need to support an ancient browser that doesn't support this feature, this is a polyfill suggested by the MDN :

if (!String.prototype.trim) {
    String.prototype.trim = function () {
       return this.replace(/^[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+$/g, '');
    };
}

Answer 17

Using trim() on String which is a native could be the easiest way:

 const fullName = " Alireza Dezfoolian "; const trimmedFullName = fullName.trim(); console.log(trimmedFullName); 

Answer 18

I have a lib that uses trim. so solved it by using the following code.

String.prototype.trim = String.prototype.trim || function(){ return jQuery.trim(this); };

Answer 19

I had written this function for trim, when the .trim() function was not available in JS way back in 2008. Some of the older browsers still do not support the .trim() function and i hope this function may help somebody.

TRIM FUNCTION

function trim(str)
{
    var startpatt = /^\s/;
    var endpatt = /\s$/;

    while(str.search(startpatt) == 0)
        str = str.substring(1, str.length);

    while(str.search(endpatt) == str.length-1)
        str = str.substring(0, str.length-1);   

    return str;
}

Explanation : The function trim() accept a string object and remove any starting and trailing whitespaces (spaces,tabs and newlines) and return the trimmed string. You can use this function to trim form inputs to ensure valid data to be sent.

The function can be called in the following manner as an example.

form.elements[i].value = trim(form.elements[i].value);

Answer 20

You can do it using the plain JavaScript:

function trimString(str, maxLen) {
if (str.length <= maxLen) {
return str;
}
var trimmed = str.substr(0, maxLen);
return trimmed.substr(0, trimmed.lastIndexOf(' ')) + '…';
}

// Let's test it

sentenceOne = "too short";
sentencetwo = "more than the max length";

console.log(trimString(sentenceOne, 15));
console.log(trimString(sentencetwo, 15));

Answer 21

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

From the previous answers, it differs adding flag m .

Flag m will search the text of several linear. In this mode, the mark the beginning and end of the pattern ( ^ $ ) is inserted before and after the newline character ( \\n ).

Answer 22

Don't know what bugs can hide here, but I use this:

var some_string_with_extra_spaces="   goes here    "
console.log(some_string_with_extra_spaces.match(/\S.*\S|\S/)[0])

Or this, if text contain enters:

console.log(some_string_with_extra_spaces.match(/\S[\s\S]*\S|\S/)[0])

Another try:

console.log(some_string_with_extra_spaces.match(/^\s*(.*?)\s*$/)[1])

Answer 23

Here it is in TypeScript:

var trim: (input: string) => string = String.prototype.trim
    ? ((input: string) : string => {
        return (input || "").trim();
    })
    : ((input: string) : string => {
        return (input || "").replace(/^\s+|\s+$/g,"");
    })

It will fall back to the regex if the native prototype is not available.

Answer 24

Now trim() build in javascript.

let yourName = ' something   ';
let actualTrimmedName = yourName.trim();

just console or print code then your name will be trimmed as well.

Answer 25

mine uses a single regex to look for cases where trimming is necessary, and uses that regex's results to determine desired substring bounds:

var illmatch= /^(\s*)(?:.*?)(\s*)$/
function strip(me){
    var match= illmatch.exec(me)
    if(match && (match[1].length || match[2].length)){
        me= me.substring(match[1].length, p.length-match[2].length)
    }
    return me
}

the one design decision that went into this was using a substring to perform the final capture. s/\?:// (make the middle term capturing) and and the replacement fragment becomes:

    if(match && (match[1].length || match[3].length)){
        me= match[2]
    }

there's two performance bets I made in these impls:

1. does the substring implementation copy the original string's data? if so, in the first, when a string needs to be trimmed there is a double traversal, first in the regex (which may, hopefully be partial), and second in the substring extraction. hopefully a substring implementation only references the original string, so operations like substring can be nearly free. cross fingers

2. how good is the capture in the regex impl? the middle term, the output value, could potentially be very long. i wasn't ready to bank that all regex impls' capturing wouldn't balk at a couple hundred KB input capture, but i also did not test (too many runtimes, sorry!). the second ALWAYS runs a capture; if your engine can do this without taking a hit, perhaps using some of the above string-roping-techniques, for sure USE IT!

Answer 26

For IE9+ and other browsers

function trim(text) {
    return (text == null) ? '' : ''.trim.call(text);
}