<pre>
function IsTrue(num){
var arr = [];
if(typeof num != 'number'){
return false;
}
if(num in arr){
return false;
}
if(num === 2){
arr.push(num);
return true;
}else if(num%2 === 0){
return false;
}
if(Number.isInteger(Math.sqrt(num))){
return false;
}
for(var i = 3; i < num; i++){
if(num%i === 0){
return false;
}
}
arr.push(num);
return true;
}
</pre>
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判断一个数字是否是整数方法:Number.isInteger(num);
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开根号方法:Math.sqrt(num)
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