如何使用JavaScript从字符串中获取前8个字符和最后8个字符？

Question

How to get first 8 char and last 8 char from srting using javascript ?

I use this code for php , How can i apply this code to javascript ?

$file_name_length = mb_strlen($file_name, 'UTF-8');
$first_char_position_last_8_char_file_name= $file_name_length-8;
$first_8_char_file_name_display = mb_substr($file_name, 0, 8,"utf-8");
$last_8_char_file_name_display = mb_substr($file_name, $first_char_position_last_8_char_file_name, 8,"utf-8");

Answer 1

You can use String.prototype.substr() :

var data = '12345678whatever87654321';

data.substr(0, 8); // 12345678
data.substr(-8); // 87654321

Answer 2

You can do it with substring like this:

var str = "some string with many chars";
var newstr=str.substring(0,8)+str.substr(str.length-8);

Answer 3

You can use String.slice or String.substring

In your case this should work:

var string = 'Hello nice nice world';

// with substring
console.log(string.substring(0, 8), string.substring(string.length - 8, string.length)); // Hello ni ce world

// with slice
console.log(string.slice(0, 8), string.slice(string.length - 8, string.length)); // Hello ni ce world

Answer 4

Using the same variable names you will have:

var file_name_length = file_name.length;
var first_char_position_last_8_char_file_name= file_name_length - 8;
var first_8_char_file_name_display = file_name.substr(0, 8);
var last_8_char_file_name_display = file_name.substr(first_char_position_last_8_char_file_name, 8);