[ 자바스크립트 ] 0, +0, -0

자바스크립트에서의 0. ( Zero in javascript )

 
<button onclick="testing()"> Click me </button>
<p id="demo1">   </p>
<p id="demo2">   </p>

<script>
function testing (){
    var x = ""; 
    document.getElementById( "demo1" ).innerHTML = 0 == x; 
    document.getElementById( "demo2" ).innerHTML = 0 === x; 
}
</script>
 

0 == +0	➜	0 === +0	➜	0 != +0	➜	0 !== +0	➜
0 == -0	➜	0 === -0	➜	0 != -0	➜	0 !== -0	➜
0 == false	➜	0 === false	➜	0 != false	➜	0 !== false	➜
0 == ""	➜	0 === ""	➜	0 != ""	➜	0 !== ""	➜
0 == [ ]	➜	0 === [ ]	➜	0 != [ ]	➜	0 !== [ ]	➜

 
<button onclick="testing()"> Click me </button>
<p id="demo3">   </p>
<p id="demo4">   </p>

<script>
function isZero ( x ){  return x === 0;  } 

function testing (){
    var num = 0; 
    var str = ""; 
    document.getElementById( "demo3" ).innerHTML = isZero( num ); 
    document.getElementById( "demo4" ).innerHTML = isZero( str ); 
}
</script>
 

isZero( +0 )	➜
isZero( -0 )	➜
isZero( false )	➜
isZero( "" )	➜
isZero( [ ] )	➜

 
<button onclick="testing()"> Click me </button>
<p id="demo5">   </p>
<p id="demo6">   </p>

<script>
function testing (){
    var a = 1 / +0; 
    var b = 1 / -0; 
    document.getElementById( "demo5" ).innerHTML = a; 
    document.getElementById( "demo6" ).innerHTML = b; 
}
</script>
 

 
function isNegativeZero ( x ){  return x === 0 && (1/x) === -Infinity;  } 
 

isNegativeZero( -0 )	➜
isNegativeZero( +0 )	➜
isNegativeZero( 0 )	➜

https://tonks.tistory.com/236#_zero_in_javascript

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