CODEWITHSUNDEEP
javascriptregex
nakul89
nakul89

Reputation: 147

< followed by space or not in regex

I have a multi-line textbox, if I enter below string:

index a<3

2<x

By using regex I need to add space after character '<' if there is no space. And if already have space after character '<' then keep as it is don't add additional space.

Expected result should be:

index a< 3

2< x

I tried (?<=<)(?!$) and <[^\s]+ these but giving syntax error, when used inside Javascript.

I can use them in back end(C#) but I don't want to put server request for it, as it not a good option.

Upvotes: 1

Views: 65

Answers (3)

Pranav C Balan
Pranav C Balan

Reputation: 115242

You can use \S to match any non-space character(which is a short handler for a negated character class, [^\s]). Since Javascript doesn't support look-behind you need to match < symbol followed by non-space character and then replace it with space contained < symbol.

str = str.replace(/<(?=\S)/g, '< ');

// or with negative lookahead
str = str.replace(/<(?!\s)/g, '< ');


var str = 'index a<3\n2<x';


console.log(
  str.replace(/<(?=\S)/g, '< '),
  '\n\n',
  str.replace(/<(?!\s)/g, '< ')
)

Upvotes: 0

Uri Y
Uri Y

Reputation: 850

Use the following simple regex: <\b and replace it with < ('<' followed by a space)

Upvotes: 0

gurvinder372
gurvinder372

Reputation: 68413

See the following approach without regex (ok, only little bit of regex used in split)

document.querySelector( "textarea" ).addEventListener( "blur", function(){
  var value = this.value;
  //console.log( value );
  this.value = value.split( /\n|\r/ ).map( function(item){
    //console.log( item, item.split( /<|<\s/ ) );
    return item.split( /<\s|</ ).join( "< " );
  }).join( "\n" );
})
Focus out of the below textarea to see the space added
<textarea>
index a<3 
index a<3 
</textarea>

Upvotes: 1

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