Programing/JavaScript
Truthy and Falsy Values in JavaScript
다람지덕후
2019. 1. 23. 13:31
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function logTruthiness (val) {
if (val) {
console.log("Truthy!");
} else {
console.log("Falsy.");
}
}
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Truthy
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// Outputs: "Truthy!"
logTruthiness(true);
// Outputs: "Truthy!"
logTruthiness({});
// Outputs: "Truthy!"
logTruthiness([]);
// Outputs: "Truthy!"
logTruthiness("some string");
// Outputs: "Truthy!"
logTruthiness(3.14);
// Outputs: "Truthy!"
logTruthiness(new Date());
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Falsy
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// Outputs: "Falsy."
logTruthiness(false);
// Outputs: "Falsy."
logTruthiness(null);
// Outputs: "Falsy."
logTruthiness(undefined);
// Outputs: "Falsy."
logTruthiness(NaN);
// Outputs: "Falsy."
logTruthiness(0);
// Outputs: "Falsy."
logTruthiness("");
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Truthy Falsy 예문
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function reportAttitude (person) {
if (person.skepticism) {
console.log(person.name +
" is skeptical about " +
person.skepticism);
} else {
console.log(person.name + " wants to believe.");
}
}
var mulder = {
name: "Fox Mulder"
};
var scully = {
name: "Dana Scully",
skepticism: "UFOs & conspiracy theories"
};
var frohikey = {
name: "Melvin Frohikey",
skepticism: ""
};
// Outputs: "Fox Mulder wants to believe."
reportAttitude(mulder);
// Outputs: "Dana Scully is skeptical about UFOs and conspiracy theories."
reportAttitude(scully);
// Outputs: "Melvin Frohikey wants to believe."
reportAttitude(frohikey);
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출처 : http://adripofjavascript.com/blog/drips/truthy-and-falsy-values-in-javascript.html