**`isSafeInteger()`** is a `Number` method that is used to determine if a given value is a safe integer. A **safe integer** is an integer that is in the range -($2^{53}$ - 1) to ($2^{53}$ - 1).
# Declaration
 The `isSafeInteger()` method is declared as follows:
```js
Number.isSafeInteger(value)
```
* `value`: The value to be tested to check whether it is a safe integer or not.

# Return value
The `isSafeInteger()` method returns a boolean depending on the `value` as follows:
* The `isSafeInteger()` method returns `false` if `value` is not a safe integer.
* The `isSafeInteger()` method returns `true` if `value` is a safe integer. 
 

# Browser compatibility
The `isSafeInteger()` method is supported by the following browsers:
* Edge 12
* Firefox 32
* Google Chrome 19
* Opera 22
* Safari 9




# Examples
## Example 1
Consider the code snippet below, which demonstrates the use of the `isSafeInteger()` method:

var foo = Number.isSafeInteger( -(Math.pow(2, 53)-1) ) // -2^53 - 1
console.log("Given value is integer: ",foo);

var foo = Number.isSafeInteger(0)
console.log("Given value is integer: ",foo);

var foo = Number.isSafeInteger(Math.pow(2, 53)-1) // 2^53 - 1
console.log("Given value is integer: ",foo);

## Explanation
Positive, negative, and 0 integers are passed to the `isSafeInteger()` method in *line 1*, *line 4*, and *line 7*, respectively. The `isSafeInteger()` method returns `true`, as the given values are integers in the range -($2^{53}$ - 1) to ($2^{53}$ - 1).

## Example 2
Consider the code snippet below, in which non-integers and non-safe integers are passed to the `isSafeInteger()` method:

var foo = Number.isSafeInteger("123") 
console.log("Given value is integer: ",foo);

var foo = Number.isSafeInteger(11.7)
console.log("Given value is integer: ",foo);

var foo = Number.isSafeInteger(Infinity)
console.log("Given value is integer: ",foo);

var foo = Number.isSafeInteger(NaN)
console.log("Given value is integer: ",foo);

var foo = Number.isSafeInteger(true)
console.log("Given value is integer: ",foo);

var foo = Number.isSafeInteger(Math.PI)
console.log("Given value is integer: ",foo);

var foo = Number.isSafeInteger([1])
console.log("Given value is integer: ",foo);

var foo = Number.isSafeInteger(Math.pow(2, 53)+1) // 2^53 + 1
console.log("Given value is integer: ",foo);


## Explanation
Non-integers and non-safe integers are passed to the `isSafeInteger()` method in the code snippet above. The `isSafeInteger()` method returns `false` for the non-integers and non-safe integers.

What is isSafeInteger() in Javascript?

Determines if a value is a safe integer within the range -(2\^53 - 1) to 2\^53 - 1.