JSFiddle - React, Tailwind, and code Playground

HTML

<form name="trabalheConoscoFormulario" id="trabalheConoscoFormulario" action="" method="post" onsubmit="return trabalheConoscoForm();">
    <div class="grid_210 f-left">
        <input type="text" placeholder="nome*" />
        <input type="text" placeholder="e-mail*" />
        <input type="text" placeholder="telefone" />
        <input class="grid_150 f-left" type="text" placeholder="cidade" />
        <input class="grid_55 f-right" type="text" placeholder="UF" />
        <div class="clear"></div>
        <div class="flechaPreta flechaBrancaTrabalhe margin-top-10 cp"></div>
    </div>
    <div class="grid_210 f-right">
        <div class="trabalheConoscoAnexo cp">anexar curr&iacute;culo</div>
        <input style="display:none" type="file" class="trabalheConoscoAnexoInput" id="curriculoForm" name="curriculoForm" value="" />
        <textarea type="text" id="trabalheConoscoObs" name="trabalheConoscoObs" placeholder="observa&ccedil;&otilde;es"></textarea>
    </div>
</form>

JavaScript

function add() {
    if ($(this).val() == '') {
        $(this).val($(this).attr('placeholder')).addClass('placeholder');
    }
}

function remove() {
    if ($(this).val() == $(this).attr('placeholder')) {
        $(this).val('').removeClass('placeholder');
    }
}
if (!('placeholder' in $('<input>')[0])) { // Create a dummy element for feature detection
    $('input[placeholder], textarea[placeholder]').blur(add).focus(remove).each(add); 
    $('form').submit(function () {
        $(this).find('input[placeholder], textarea[placeholder]').each(remove);
    }); 
}