How does javascript determine whether it contains a specified string

This article is about how to determine whether javascript contains a specified string, the editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

Judgment method: 1, use the indexOf () method to get the first occurrence position of the specified string value, if the return value is "- 1", it does not contain; 2, use the search () method to retrieve the specified string, if the return value is "- 1", it does not contain; 3, use the match () method; 4, use the test () method, and so on.

The operating environment of this tutorial: windows7 system, javascript1.8.5 version, Dell G3 computer.

JavaScript determines whether a string contains a specified string

Method 1: indexOf () (recommended)

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

Var str = "123"; console.log (str.indexOf (" 3 ")! =-1); / / true

Method 2: search ()

The search () method is used to retrieve a specified substring in a string, or to retrieve a substring that matches a regular expression, and returns-1 if no matching substring is found.

Var str= "123"; console.log (str.search ("3")! =-1); / / true

Method 3: match ()

The match () method retrieves the specified value within a string or finds a match of one or more regular expressions.

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

Method 4: test ()

The test () method is used to retrieve the value specified in the string. Return true and false.

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

Method 5: exec ()

The exec method is used to retrieve the match of a regular expression in a string. Returns an array containing the matching results. If no match is found, the return value is null.

Var str= "123"; reg=RegExp (/ 3 /); if (reg.exec (str)) {/ / contains} JavaScript is the abbreviation of JavaScript, it is a literal scripting language, its interpreter is called JavaScript engine, is a part of the browser, mainly used for web development, can add a variety of dynamic effects to the website, make the page more beautiful.

This is how javascript determines whether it contains a specified string. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.