Implementation of sprintf and printf functions in JavaScript _ javascript skills

This article mainly introduces the implementation of sprintf and printf functions in JavaScript. These two functions are available in most programming languages, but not in JS. This article introduces how to implement these two functions in js, for more information about how to implement the sprintf/printf function in most languages, see JavaScript.

Http://www.webtoolkit.info/javascript-sprintf.html: relatively complete simulation of sprintf functions. Available formatting wildcards:
1. %-return percentage itself
2.% B-binary number
3. characters corresponding to % c-ASCII
4.% d-integer
5.% f-floating point number
6.% o-octal digit
7.% s-string
8.% x-16 digits (in lower case)
9.% X-16 digits (uppercase letters)

Options available between the % and wildcard characters include (for example, %. 2f ):

1. + (force the + and-signs to be displayed before the number to mark them as positive and negative numbers. By default, only negative numbers are displayed.-symbol)
2.-(variable left alignment)
3.0 (use 0 as the padding character on the right alignment)
4. [0-9] (set the minimum width of the variable)
5. [0-9] (set the floating point precision or string length)

The code is as follows:

/**
*
* Javascript sprintf
* Http://www.webtoolkit.info/
*
*
**/

SprintfWrapper = {

Init: function (){

If (typeof arguments = "undefined") {return null ;}
If (arguments. length <1) {return null ;}
If (typeof arguments [0]! = "String") {return null ;}
If (typeof RegExp = "undefined") {return null ;}

Var string = arguments [0];
Var exp = new RegExp (/(% ([%] | (\-)? (\ + | \ X20 )? (0 )? (\ D + )? (\. (\ D )?)? ([BcdfosxX])/g );
Var matches = new Array ();
Var strings = new Array ();
Var convCount = 0;
Var stringPosStart = 0;
Var stringPosEnd = 0;
Var matchPosEnd = 0;
Var newString = '';
Var match = null;

While (match = exp.exe c (string )){
If (match [9]) {convCount + = 1 ;}

StringPosStart = matchPosEnd;
StringPosEnd = exp. lastIndex-match [0]. length;
Strings [strings. length] = string. substring (stringPosStart, stringPosEnd );

MatchPosEnd = exp. lastIndex;
Matches [matches. length] = {
Match: match [0],
Left: match [3]? True: false,
Sign: match [4] | '',
Pad: match [5] | '',
Min: match [6] | 0,
Precision: match [8],
Code: match [9] | '% ',
Negative: parseInt (arguments [convCount]) <0? True: false,
Argument: String (arguments [convCount])
};
}
Strings [strings. length] = string. substring (matchPosEnd );

If (matches. length = 0) {return string ;}
If (arguments. length-1) <convCount) {return null ;}

Var code = null;
Var match = null;
Var I = null;

For (I = 0; I

If (matches [I]. code = '%') {substitution = '% '}
Else if (matches [I]. code = 'B '){
Matches [I]. argument = String (Math. abs (parseInt (matches [I]. argument). toString (2 ));
Substitution = sprintfWrapper. convert (matches [I], true );
}
Else if (matches [I]. code = 'C '){
Matches [I]. argument = String (String. fromCharCode (parseInt (Math. abs (parseInt (matches [I]. argument )))));
Substitution = sprintfWrapper. convert (matches [I], true );
}
Else if (matches [I]. code = 'd '){
Matches [I]. argument = String (Math. abs (parseInt (matches [I]. argument )));
Substitution = sprintfWrapper. convert (matches [I]);
}
Else if (matches [I]. code = 'F '){
Matches [I]. argument = String (Math. abs (parseFloat (matches [I]. argument). toFixed (matches [I]. precision? Matches [I]. precision: 6 ));
Substitution = sprintfWrapper. convert (matches [I]);
}
Else if (matches [I]. code = 'O '){
Matches [I]. argument = String (Math. abs (parseInt (matches [I]. argument). toString (8 ));
Substitution = sprintfWrapper. convert (matches [I]);
}
Else if (matches [I]. code ='s '){
Matches [I]. argument = matches [I]. argument. substring (0, matches [I]. precision? Matches [I]. precision: matches [I]. argument. length)
Substitution = sprintfWrapper. convert (matches [I], true );
}
Else if (matches [I]. code = 'x '){
Matches [I]. argument = String (Math. abs (parseInt (matches [I]. argument). toString (16 ));
Substitution = sprintfWrapper. convert (matches [I]);
}
Else if (matches [I]. code = 'x '){
Matches [I]. argument = String (Math. abs (parseInt (matches [I]. argument). toString (16 ));
Substitution = sprintfWrapper. convert (matches [I]). toUpperCase ();
}
Else {
Substitution = matches [I]. match;
}

NewString + = strings [I];
NewString + = substitution;

}
NewString + = strings [I];

Return newString;

},

Convert: function (match, nosign ){
If (nosign ){
Match. sign = '';
} Else {
Match. sign = match. negative? '-': Match. sign;
}
Var l = match. min-match. argument. length + 1-match. sign. length;
Var pad = new Array (l <0? 0: l). join (match. pad );
If (! Match. left ){
If (match. pad = "0" | nosign ){
Return match. sign + pad + match. argument;
} Else {
Return pad + match. sign + match. argument;
}
} Else {
If (match. pad = "0" | nosign ){
Return match. sign + match. argument + pad. replace (/0/g ,'');
} Else {
Return match. sign + match. argument + pad;
}
}
}
}

Sprintf = sprintfWrapper. init;

If you only want to replace the content of a simple location variable without additional formatting, you can use the printf provided in simple YUI tools:

The code is as follows:

YAHOO. Tools. printf = function (){
Var num = arguments. length;
Var oStr = arguments [0];
For (var I = 1; I <num; I ++ ){
Var pattern = "\ {" + (i-1) + "\\}";
Var re = new RegExp (pattern, "g ");
OStr = oStr. replace (re, arguments [I]);
}
Return oStr;
}

When used, it is like YAHOO. Tools. printf ("display string {0}, {1 }. "," 1 "," 2 "); use {?} For matching.