f=
n=>!(n**.5%1)
console.log(f(0));
console.log(f(1));
console.log(f(2));
console.log(f(4));
console.log(f(8));
console.log(f(16));
console.log(f(88));
console.log(f(2147483647));

#JavaScript (ES6), 13 bytes

n=>!(n**.5%1)

Returns true if the square root of n is a whole number.

Snippet:

f=
n=>!(n**.5%1)
console.log(f(0));
console.log(f(1));
console.log(f(2));
console.log(f(4));
console.log(f(8));
console.log(f(16));
console.log(f(88));
console.log(f(2147483647));

JavaScript (ES6), 13 bytes

n=>!(n**.5%1)

Returns true if the square root of n is a whole number.

Snippet:

f=
n=>!(n**.5%1)
console.log(f(0));
console.log(f(1));
console.log(f(2));
console.log(f(4));
console.log(f(8));
console.log(f(16));
console.log(f(88));
console.log(f(2147483647));