How to check if TextBox control has value in JQuery

Question

I want to check some Textbox control if they have value do some addition else do assignment I used the JQuery script below it didn't work for me. The idea is on key up it should call the JQuery Function to check if TextBox797 have value then sum up the value of TextBox651 and TextBox797 else replace the value of TextBox797 with value of TextBox651. it not showing any result ASP:TextBox ID = TextBox651 runAt = server onKeyUp = CheckIT() /> ASP:TextBox ID = TextBox797 runAt = server /> this is the JQ script i have in the Function function CheckIT() { if ($( '# ' ).val() !=  && $( '# ' ).val() >= 0) { document.getElementById( ' ' ).value = parseInt(document.getElementById( ' ' ).value) + parseInt(document.getElementById( ' ' ).value); } else { document.getElementById( ' ' ).value = parseInt(document.getElementById( ' ' ).value); } } please is their any other way to write the JQuery to do the job ? Thank you

Suraj Binorkar · Answer

By using jQuery selectors for selecting the elements you have a jQuery object and you should use val() method for getting/setting value of input elements function checking() { var textBox = $.trim( $('input[type=text]').val() ) if (textBox == ) { $(#error).show('slow'); } } If you want to use value property you should first convert the jQuery object to a raw DOM object. You can use [index] or get method. var textBox = $('input[type=text]')[0].value; If you have multiple inputs you should loop through them. function checking() { var empty = 0; $('input[type=text]').each(function(){ if (this.value == ) { empty++; $(#error).show('slow'); } }) alert(empty + ' empty input(s)') } Hope this may be help you to solve your question :) Happy Programming :)

Suraj Binorkar · Answer

By using jQuery selectors for selecting the elements you have a jQuery object and you should use val() method for getting/setting value of input elements function checking() { var textBox = $.trim( $('input[type=text]').val() ) if (textBox == ) { $(#error).show('slow'); } } If you want to use value property you should first convert the jQuery object to a raw DOM object. You can use [index] or get method. var textBox = $('input[type=text]')[0].value; If you have multiple inputs you should loop through them. function checking() { var empty = 0; $('input[type=text]').each(function(){ if (this.value == ) { empty++; $(#error).show('slow'); } }) alert(empty + ' empty input(s)') } Hope this may be help you to solve your question :) Happy Programming :)

Suraj Binorkar · Answer

By using jQuery selectors for selecting the elements you have a jQuery object and you should use val() method for getting/setting value of input elements function checking() { var textBox = $.trim( $('input[type=text]').val() ) if (textBox == ) { $(#error).show('slow'); } } If you want to use value property you should first convert the jQuery object to a raw DOM object. You can use [index] or get method. var textBox = $('input[type=text]')[0].value; If you have multiple inputs you should loop through them. function checking() { var empty = 0; $('input[type=text]').each(function(){ if (this.value == ) { empty++; $(#error).show('slow'); } }) alert(empty + ' empty input(s)') } Hope this may be help you to solve your question :) Happy Programming :)