# LESS - Type Functions

In this chapter, we will understand the importance of Type Functions in LESS. They are used to determine the type of the value.

The following table shows the Type Functions used in LESS.

Sr.No. Type Functions & Description Example
1

isnumber

It takes a value as parameter and returns true, if it's a number or false otherwise.

```isnumber(1234);       // true
isnumber(24px);       // true
isnumber(7.8%);       // true
isnumber(#fff);       // false
isnumber(red);        // false
isnumber("variable"); // false
isnumber(keyword);    // false
isnumber(url(...));   // false
```
2

isstring

It takes a value as parameter and returns true, if it's a string or false otherwise.

```isstring("variable"); // true
isstring(1234);       // false
isstring(24px);       // false
isstring(7.8%);       // false
isstring(#fff);       // false
isstring(red);        // false
isstring(keyword);    // false
isstring(url(...));   // false
```
3

iscolor

It takes a value as parameter and returns true, if value is a color or false if it's not.

```iscolor(#fff);        // true
iscolor(red);         // true
iscolor(1234);        // false
iscolor(24px);        // false
iscolor(7.8%);        // false
iscolor("variable");  // false
iscolor(keyword);     // false
iscolor(url(...));    // false
```
4

iskeyword

It takes a value as parameter and returns true, if value is a keyword or false if it's not.

```iskeyword(keyword);   // true
iskeyword(1234);      // false
iskeyword(24px);      // false
iskeyword(7.8%);      // false
iskeyword(#fff);      // false
iskeyword(red) ;      // false
iskeyword("variable");// false
iskeyword(url(...));  // false
```
5

isurl

It takes a value as parameter and returns true, if value is a url or false if it's not.

```isurl(url(...));      // true
isurl(keyword);       // false
isurl(1234);          // false
isurl(24px);          // false
isurl(7.8%);          // false
isurl(#fff);          // false
isurl(red) ;          // false
isurl("variable");    // false
```
6

ispixel

It takes a value as parameter and returns true, if value is a number in pixels or false otherwise.

```ispixel(24px);          // true
ispixel(1234);          // false
ispixel(7.8%);          // false
ispixel(keyword);       // false
ispixel(#fff);          // false
ispixel(red) ;          // false
ispixel("variable");    // false
ispixel(url(...));      // false
```
7

isem

It takes a value as parameter and returns true, if value is an em value or false if it's not.

```isem(0.5em);            // true
isem(1234);             // false
isem(24px);             // false
isem(keyword);          // false
isem(#fff);             // false
isem(red) ;             // false
isem("variable");       // false
isem(url(...));         // false
```
8

ispercentage

It takes a value as parameter and returns true, if value is in percentage or returns false, if value is not in percentage.

```ispercentage(7.5%);       // true
ispercentage(url(...));   // false
ispercentage(keyword);    // false
ispercentage(1234);       // false
ispercentage(24px);       // false
ispercentage(#fff);       // false
ispercentage(red) ;       // false
ispercentage("variable"); // false
```
9

isunit

It returns true if a value is a number in specified units provided as parameter or it will return false if value is not a number in specified units.

```isunit(10px, px);       // true
isunit(5rem, rem);      // true
isunit(7.8%, '%');      // true
isunit(2.2%, px);       // false
isunit(24px, rem);      // false
isunit(48px, "%");      // false
isunit(1234, em);       // false
isunit(#fff, pt);       // false
isunit("mm", mm);       // false
```
10

isruleset

It takes a value as parameter and returns true, if value is a ruleset or false otherwise.

```@rules: {
color: green;
}

isruleset(@rules);      // true
isruleset(1234);        // false
isruleset(24px);        // false
isruleset(7.8%);        // false
isruleset(#fff);        // false
isruleset(blue);        // false
isruleset("variable");  // false
isruleset(keyword);     // false
isruleset(url(...));    // false
```
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