[javascript] How to read line by line of a text area HTML tag

I have a text area where each line contains Integer value like follows

      1234
      4321
     123445

I want to check if the user has really enetered valid values and not some funny values like follows

      1234,
      987l;

For that I need to read line by line of text area and validate that. How can i read line by line of a text area using javascript?

This would give you all valid numeric values in lines. You can change the loop to validate, strip out invalid characters, etc - whichever you want.

var lines = [];
$('#my_textarea_selector').val().split("\n").each(function ()
{
    if (parseInt($(this) != 'NaN')
        lines[] = parseInt($(this));
}

Two options: no JQuery required, or JQuery version

No JQuery (or anything else required)

var textArea = document.getElementById('myTextAreaId');
var lines = textArea.value.split('\n');    // lines is an array of strings

// Loop through all lines
for (var j = 0; j < lines.length; j++) {
  console.log('Line ' + j + ' is ' + lines[j])
}

JQuery version

var lines = $('#myTextAreaId').val().split('\n');   // lines is an array of strings

// Loop through all lines
for (var j = 0; j < lines.length; j++) {
  console.log('Line ' + j + ' is ' + lines[j])
}

Side note, if you prefer forEach a sample loop is

lines.forEach(function(line) {
  console.log('Line is ' + line)
})

A simple regex should be efficent to check your textarea:

/\s*\d+\s*\n/g.test(text) ? "OK" : "KO"

This works without needing jQuery:

var textArea = document.getElementById("my-text-area");
var arrayOfLines = textArea.value.split("\n"); // arrayOfLines is array where every element is string of one line