JavaScript变量类型以及变量之间的转换你了解吗

<script>
        var num =10;
        console.log(typeof num);
</script>

var num=10;
var str=num.toString();
console.log(str);

var age=prompt('请输入您的年龄');
        console .log(parseInt(age));
        console.log(parseInt('3.14'));  //取整 3
        console.log(parseInt('3.98'));  //取整 3
        console.log(parseInt('120px'));  //取整 120

console.log(parseFloat('3.14'));
console.log(parseFloat('120px')); //120会去掉px单位

var str='123';
console.log(number(str);
console.log(number('123'));

console.log('12'-0); //12
console.log('123'-'120'); //3
console.log('123'*1); //123

console.log(boolean(''));//false
console.log(boolean(0));//false
console.log(boolean(NaN));//false
console.log(boolean(null));//false
console.log(boolean(undefined));//false