react-json-schema-form/validate.js

Fully customizable Fastest rendering JS/ Json Schema driven React Forms that support validations, POST , Success and Error Alerts , callbacks , React Components (Input, Switch, Checkbox, Radio) renders device o.s theme (iOS,Android and Windows) by default

var validate = function validate(validateRules, value) {
  var errorMessage = "";
  validateRules.forEach(function (vr) {
    if (vr.rule === "required" && (!value || value === "")) {
      errorMessage = vr.message ? vr.message : "This is required field";
    } else if (vr.rule === "equal") {} else if (vr.rule === "regex") {
      var regex = new RegExp(vr.expression);
      if (!regex.test(value)) {
        errorMessage = vr.message ? vr.message : "Please enter valid values";
      }
    }
  });
  return errorMessage;
};

export default validate;