JavaScript Comparison and Logical Operators - W3Schools

JavaScript also contains a conditional operator that assigns a value to a variable based on some condition. Syntax. variablename = (condition) ? value1:value2 ... 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ComparisonOperators Comparisonoperatorsareusedinlogicalstatementstodetermineequalityordifferencebetweenvariablesorvalues. Giventhatx=5,thetablebelowexplainsthecomparisonoperators: Operator Description Comparing Returns Tryit == equalto x==8 false Tryit» x==5 true Tryit» x=="5" true Tryit» === equalvalueandequaltype x===5 true Tryit» x==="5" false Tryit» != notequal x!=8 true Tryit» !== notequalvalueornotequaltype x!==5 false Tryit» x!=="5" true Tryit» x!==8 true Tryit» > greaterthan x>8 false Tryit» < lessthan x<8 true Tryit» >= greaterthanorequalto x>=8 false Tryit» <= lessthanorequalto x<=8 true Tryit» HowCanitbeUsed Comparisonoperatorscanbeusedinconditionalstatementstocomparevalues andtakeactiondependingontheresult: if(age<18)text="Tooyoungtobuyalcohol"; Youwilllearnmoreabouttheuseofconditionalstatementsinthenextchapterofthistutorial. LogicalOperators Logicaloperatorsareusedtodeterminethelogicbetweenvariablesorvalues. Giventhatx=6andy=3,thetablebelowexplainsthelogicaloperators: Operator Description Example Tryit && and (x<10&&y>1)istrue Tryit» || or (x==5||y==5)isfalse Tryit» ! not !(x==y)istrue Tryit» Conditional(Ternary)Operator JavaScriptalsocontainsaconditionaloperatorthatassignsavaluetoavariablebasedonsomecondition. Syntax variablename=(condition)?value1:value2  Example letvoteable=(age<18)?"Tooyoung":"Oldenough"; TryitYourself» Ifthevariableageisavaluebelow18,thevalueofthevariablevoteable willbe"Tooyoung",otherwisethevalueofvoteablewillbe"Oldenough". ComparingDifferentTypes Comparingdataofdifferenttypesmaygiveunexpectedresults. Whencomparingastringwithanumber,JavaScriptwillconvertthestringto anumberwhendoingthecomparison.Anemptystringconvertsto0.Anon-numeric stringconvertstoNaNwhichisalwaysfalse. Case Value Try 2<12 true Tryit» 2"John" false Tryit» 2=="John" false Tryit» "2""12" true Tryit» "2"=="12" false Tryit» Whencomparingtwostrings,"2"willbegreaterthan"12",because (alphabetically)1islessthan2. Tosecureaproperresult,variablesshouldbeconvertedtothepropertype beforecomparison: age=Number(age); if(isNaN(age)){   voteable="Inputisnotanumber"; }else{  voteable=(age<18)?"Tooyoung":"Oldenough"; } TryitYourself» TestYourselfWithExercises Exercise: Choosethecorrectcomparisonoperatortoalerttrue,whenxisgreaterthany. x=10; y=5; alert(xy); SubmitAnswer» StarttheExercise» ❮Previous Next❯ NEW WejustlaunchedW3Schoolsvideos Explorenow COLORPICKER Getcertifiedbycompletingacoursetoday! w3schoolsCERTIFIED.2022 Getstarted CODEGAME PlayGame