リチャードJavaScript(8)-ブル関連問題
1885 ワード
基本的な使い方
var b;
b = true; alert(b); //true
b = new Boolean(false); alert(b); //false
b = 2 > 1; alert(b); //true
b = 2 < 1; alert(b); //false
ブールに変換var b;
b = Boolean(123); alert(b); //true
b = Boolean('ABC'); alert(b); //true
b = Boolean(0); alert(b); //false
b = Boolean(''); alert(b); //false
b = Boolean(NaN); alert(b); //false
b = Boolean(null); alert(b); //false
b = Boolean(undefined); alert(b); //false
b = Boolean(Infinity); alert(b); //true
b = Boolean('false'); alert(b); //true
直接使用する自動変換var X;
if (X) {alert('ok')} else {alert('no')}; //no
X = 'ABC';
if (X) {alert('ok')} else {alert('no')}; //ok
X = '';
if (X) {alert('ok')} else {alert('no')}; //no
X = -1;
if (X) {alert('ok')} else {alert('no')}; //ok
X = 0;
if (X) {alert('ok')} else {alert('no')}; //no
X = new Date();
if (X) {alert('ok')} else {alert('no')}; //ok
ブール演算var b;
b = !b; alert(b); //false
b = !b; alert(b); //true
b = true && true; alert(b); //true
b = true && false; alert(b); //false
b = false && true; alert(b); //false
b = false && false; alert(b); //false
b = true || true; alert(b); //true
b = true || false; alert(b); //true
b = false || true; alert(b); //true
b = false || false; alert(b); //false