JS determines that a string contains a content summary

This time I will bring you JS to judge that a certain string contains a content summary. What are the precautions to use JS to judge that a certain string contains a content summary. The following is a practical case. , let’s take a look.

String object methods

Method 1: indexOf() (recommended)

 var str = "123"
 console.log(str.indexOf("2") != -1); // true

The indexOf() method returns the first occurrence of a specified string value in a string. If the string value to be retrieved does not appear, the method returns -1.

Method 2: match()

 var str = "123"
var reg = RegExp(/3/);
if(str.match(reg)){
  //包含；
}

The match() method can retrieve the specified value within the string, or find one or more A match of regular expression.

Method 3: search()

 var str = "123"
 console.log(str.search("2") != -1); // true

The search() method is used to retrieve the substring specified in the string, or retrieve the same Regular expression matching substring. If no matching substring is found, -1 is returned.

Methods of RegExp object

##Method 4: test()

 var str = "123"
var reg = RegExp(/3/);
 console.log(reg.test(str) != -1); // true

The test() method is used to retrieve the value specified in a string. Returns true or false.

Method 5: exec()

 var str = "123"
var reg = RegExp(/3/);
if(reg.exec(str)){
  //包含；
}

exec() method is used for retrieval Regular expression matching in strings. Returns an array containing the matching results. If no match is found, the return value is null.

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