Global object builtin properties delete NaN : false NaN : NaN delete Infinity : false Infinity : Infinity delete undefined : false undefined : undefined NaN= "hello"; : hello NaN : NaN Infinity= "hello"; : hello Infinity : Infinity undefined= "hello"; : hello undefined : undefined Math Object builtin properties Math.PI = overwrite : hello Math.PI : 3.141592653589793 Math.E = overwrite : hello Math.E : 2.718281828459045 Math.LN10 = overwrite : hello Math.LN10 : 2.302585092994046 Math.LN2 = overwrite : hello Math.LN2 : 0.6931471805599453 Math.LOG2E = overwrite : hello Math.LOG2E : 1.4426950408889633 Math.LOG10E = overwrite : hello Math.LOG10E : 0.4342944819032518 Math.SQRT1_2 = overwrite : hello Math.SQRT1_2 : 0.7071067811865476 Math.SQRT2 = overwrite : hello Math.SQRT2 : 1.4142135623730951 delete Math.PI : false Math.PI : 3.141592653589793 delete Math.E : false Math.E : 2.718281828459045 delete Math.LN10 : false Math.LN10 : 2.302585092994046 delete Math.LN2 : false Math.LN2 : 0.6931471805599453 delete Math.LOG2E : false Math.LOG2E : 1.4426950408889633 delete Math.LOG10E : false Math.LOG10E : 0.4342944819032518 delete Math.SQRT1_2 : false Math.SQRT1_2 : 0.7071067811865476 delete Math.SQRT2 : false Math.SQRT2 : 1.4142135623730951 Number Object builtin properties Number.MAX_VALUE = overwrite : hello Number.MAX_VALUE : 1.7976931348623157e+308 Number.MIN_VALUE = overwrite : hello Number.MIN_VALUE : 5e-324 Number.NaN = overwrite : hello Number.NaN : NaN Number.NEGATIVE_INFINITY = overwrite : hello Number.NEGATIVE_INFINITY : -Infinity Number.POSITIVE_INFINITY = overwrite : hello Number.POSITIVE_INFINITY : Infinity delete Number.MAX_VALUE : false Number.MAX_VALUE : 1.7976931348623157e+308 delete Number.MIN_VALUE : false Number.MIN_VALUE : 5e-324 delete Number.NaN : false Number.NaN : NaN delete Number.NEGATIVE_INFINITY : false Number.NEGATIVE_INFINITY : -Infinity delete Number.POSITIVE_INFINITY : false Number.POSITIVE_INFINITY : Infinity delete Number.undefined : true Number.undefined : undefined delete Number.undefined : true Number.undefined : undefined delete Number.undefined : true Number.undefined : undefined