原始值轉化為原始值

1、原始值轉化為原始值

<script type="text/javascript">
	console.log({}==!{}); //false
	console.log([]==![]); //true
	
	console.log(Number(undefined)); //NaN
	console.log(Number(null)); //0
	
	console.log(Boolean(undefined)); //false
	console.log(Boolean(null)); //false
	
        //Infinity 雖然無法表示為具體數字，但可以理解為一個數字
	console.log(Number(Infinity)); //Infinity
	console.log(Boolean(Infinity)); //true
	
        // ‘’不等於‘ ’，加空格為表示空格的字串，只有引號為虛值
	console.log(Boolean('')); //false
	console.log(Boolean(' ')); //true
</script>
 

falsey(虛值)

• undefined
• null
• 0
• NaN
• false
• ''
• (+0,-0)

Boolean型別轉換除虛值外都為true

        console.log(Boolean(undefined)); //false
	console.log(Boolean(null)); //false
	console.log(Boolean(0)); //false
	console.log(Boolean(NaN)); //false
	console.log(Boolean(false)); //false
	console.log(Boolean('')); //false
	
	console.log(Boolean(0)); //false
	console.log(Boolean(+0)); //false
	console.log(Boolean(-0)); //false