JavaScript advanced (7) differences between the substr and substring methods for intercepting strings in JS

If the length is 0 or negative, an empty string is returned. If this parameter is not specified, the substring will continue to the end of stringvar. Differences between the substr method and the substring method of JS string Truncation

Returns a substring of the specified length starting from the specified position.

Stringvar. substr (start [, length])

Parameters

Stringvar

Required. The String text or String object to extract the substring.

Start

Required. The starting position of the required substring. The index of the first character in the string is 0.

Length

Optional. The number of characters to be included in the returned substring.

Description

If the length is 0 or negative, an empty string is returned. If this parameter is not specified, the substring will continue to the end of stringvar.

Example

The following example demonstrates the substr method usage.

Function SubstrDemo () {var s, ss; // declare the variable. Var s = "The rain in Spain falls mainly in the plain."; ss = s. substr (12, 5); // obtain The substring. Return (ss); // return "Spain ".}

Substring Method

Returns the substring at the specified position in the String object.

StrVariable. substring (start, end)

"String Literal". substring (start, end)

Parameters

Start

Specifies the starting position of the substring. The index starts from 0.

End

Specifies the end position of the substring. The index starts from 0.

Description

The substring method returns a string that contains a substring from start to the end (excluding end.

The substring method uses a small value in start and end as the starting point of the substring. For example, strvar. substring (0, 3) and strvar. substring (3, 0) return the same substring.

If start or end is NaN or negative, replace it with 0.

The length of the substring is equal to the absolute value of the difference between start and end. For example, the length of the substring returned in strvar. substring (0, 3) and strvar. substring (3, 0) is 3.

Example

The following example demonstrates the usage of the substring method.

Function SubstringDemo () {var ss; // declare the variable. Var s = "The rain in Spain falls mainly in the plain .."; ss = s. substring (12, 17); // obtain The substring. Return (ss); // return the substring .}

The above is the difference between the substr method and the substring method of JavaScript advanced (7) JS truncation string. For more information, see PHP Chinese website (www.php1.cn )!