js code to limit the input string length of each line of textarea_form special effects

But textarea does not have this attribute.

The server-side textbox attribute of asp.net does not work, so we can only use js script to control it
Okay, without further ado, let’s start with the code

javascipt source code:

Copy code The code is as follows:

function textCounter(field, maxlimit, lines) {//Parameter description: field is a textarea object, maxlimit is the maximum allowed length, lines is the number of lines
var arr = field.value.split("n");//First we need to verify the number of lines by branching symbol" ”
var perLine = "";
var value = "";
if (arr.length < lines) lines = arr.length; // Determine whether the number of lines exceeds the number of lines we specify , if it exceeds, change the number of lines to the exceeded, because we need to calculate the string length
for (loop = 0; loop < lines; loop ) {//Loop to measure the total length of the string, not much to say
perLine = arr[loop];
if (perLine.length > maxlimit)
perLine = perLine.substring(0, maxlimit);
value = value perLine;
if ( loop != lines - 1)
value = value "n";
}
if (field.value != value)
field.value = value;
if (checkstr(value , maxlimit)) {//Determine whether the string length exceeds the standard
field.value = value.substring(0, maxlimit);//Delete the excess string
}
}

function showOverWords(obj, maxlength) {//Display the remaining number of input characters obj is a txteara object, maxlength maximum length
len = obj.value.length;
$("#wordCount"). html(maxlength - len); //This sentence is from jquery, you can change it yourself. It means modifying the value of id to wordCount tag
}

function checkstr(str, digit) {// Determine whether the length of the string exceeds the standard in Chinese and English
var n = 0;
for (i = 0; i < str.length; i ) {
var leg = str.charCodeAt(i) ;//ASCII code
if (leg > 255) {//Anything greater than 255 is Chinese
n = 2;//If it is Chinese, it is 2 bytes
} else {
n = 1;//English, not much to say
}
}
if (n > digit) {
return true;
} else {
return false;
}
}

ok There are three functions above. We can achieve the functions we want by calling these three functions.