使用和if如何让提示框显示TRUE和false

    alert(Boolean(4));//true
    alert(Boolean(0));//false

    if ((x = 4)) {
      alert(Boolean(x));//true
    }
    if (!(x = 0)) {
      alert(Boolean(x));//false
    }

    let x = 4;
    if (x) {
      alert(Boolean(x)); //true
    }
    x = 0;
    if (!x) {
      alert(Boolean(x)); //false
    }

    if (4) {
      alert(Boolean(4));//true
    }
    if (!0) {
      alert(Boolean(0));//false
    }

if(x && !isNaN(x) && x=4){
  alert("true");
} else {
   x = 0;
  alert("false");
}

能再明确一下要求吗

你这代码本来就有问题x声明了三遍
if(x==0||isNaN(x)){
x=false
}else{
x=true;
}