js判断是否是第一次选择，数组中是否存在当前字段

var vals = [];
var text ;
form.on('select(languageList)', function (data) {
  $('select[multiple] option:selected').each(function () {
    text = $(this).text()
    // vals.push($(this).text());
    let ind = vals.indexOf(text);
    if (ind === -1) {
      vals.push(text);
    } else {
      vals.splice(ind, 1);
    }

  })
  $(".languageVal").attr("value", vals)