String method for pattern matching using JavaScript-JS Tutorial-php.cn

String method for pattern matching using JavaScript

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Release： 2018-05-19 16:05:27

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The following editor will bring you a String method that uses JavaScript to implement pattern matching. Let me share it with you now and give it as a reference for everyone.

String methods for pattern matching:

##String supports 4 methods using regular expressions:

seach() is used for retrieval. The parameter is a regular expression and returns the position of the first matching substring. If it cannot be found, it returns -1. If the parameter is not regular expression, it will first be converted into a regular expression through the RexExp constructor. The search() method does not support global search, and it ignores the modifier g;

replace() is used for retrieval and replacement operations. Chapter One parameter is a regular expression, and the second parameter is the string to be replaced. It searches the string that calls this method and replaces the substring with the second parameter according to the pattern. If the modifier g is included, the full text is matched. If the first parameter is not a regular expression but a string, the string will be searched and replaced directly;

text.replace(/javascript/gi,'JavaScript') means that the search will not distinguish in the full text of the text. Replace uppercase and lowercase javascript with JavaScript

If ($ plus a number) appears in the string used for replacement, the replace() method will replace it with text that matches the subexpression represented by $ plus a number. , such as:

var quote = /"([^"]*)"/g

text.replace(quote,'"$1"'); Full text search and /"([^ "]*)"/matching string, replaced with "$1" (meaning only changing the double quotes on both sides to Chinese half-width, and the content stored in $1 remains unchanged) $1 stores the reference and the first left parenthesis The string matched by the subexpression within;

match()’s only parameter is a regular expression, and it returns an array composed of matching results. If the parameter is not a regular expression, it will first be passed The RexExp constructor converts it into a regular expression;

(2) If this regular expression has the modifier g, the array elements returned by match() are all the strings obtained by matching the full text;

(2) If this regular expression does not have the modifier g, match() only retrieves the first match, but it also returns an array (the first element of the array is the entire matched string, and the following elements Is the string matched by all subexpressions enclosed in parentheses in the expression, each element corresponds to a parenthesis)

For example:

var url = /(\w*):\/\/([\w.]+)\/(\S*)/;
  var text = &#39;http://www.w3school.com.cn/jsref&#39;;
  var result = text.match(url);
  if(result != null) {
  var fullurl = result[0];
  var protocol =result[1];
  var host = result[2];
  var path = result[3];
}

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split() splits the string according to the parameters The specified delimiter is split into an array composed of multiple substrings, such as:

'123,345,789'.split(','); //Return ['123','345','789']

'1, 2, 3, 4,5, 6'.split(/\s*,\s*/); //Return ['1','2','3','4 ','5','6']

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

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