Error: Attempted to access the 'state' property of an undefined object

I am working with the following function:

extractCountries: function() {
    var newLocales = [];
    _.forEach(this.props.countries, function(locale) {

        var monthTemp = Utils.thisMonthTemp(parseFloat(locale["name"]["temperature"]));

        if(parseFloat(locale["name"]["safety"]) > this.state.minSafety &&
           parseFloat(locale["name"]["nature"]) > this.state.minNature &&
           this.state.weather.min <= monthTemp &&
           monthTemp <= this.state.weather.max) {

            newLocales.push(locale);
        }
    }).bind(this);
    return newLocales;
  }

When I reach the line 

parseFloat(locale["name"]["safety"]) > this.state.minSafety &&
, an error is thrown:

Uncaught TypeError: Cannot read property 'state' of undefined

Even though I have already bound the external React object using:

}).bind(this);

What could be the reason behind this error?

javascriptreactjs

Answer №1

Give this method a try

extractCountriesData: function() {
        var filteredCountries = [];
        _.forEach(this.props.countries, function(country) {

            var tempThisMonth = Utils.thisMonthTemp(parseFloat(country["name"]["temperature"]));

            if(parseFloat(country["name"]["safety"]) > this.state.minSafety &&
               parseFloat(country["name"]["nature"]) > this.state.minNature &&
               this.state.weather.min <= tempThisMonth &&
               tempThisMonth <= this.state.weather.max) {

                filteredCountries.push(country);
            }
        }, this );
        return filteredCountries;
      }

Answer №2

To implement the solution provided in the comment, you need to follow this code snippet:

fetchCountries: function() {
    var filteredCountries = [];
    _.forEach(this.props.countries, function(country) {

        var monthTemperature = Utils.calculateMonthTemperature(parseFloat(country["name"]["temperature"]));

        if(parseFloat(country["name"]["safety"]) > this.state.minSafety &&
           parseFloat(country["name"]["nature"]) > this.state.minNature &&
           this.state.weather.min <= monthTemperature &&
           monthTemperature <= this.state.weather.max) {

            filteredCountries.push(country);
        }
    }.bind(this));
    return filteredCountries;
  }

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