type

type.js

function type(s) {
    return Object.prototype.toString.call(s).slice(8,-1).toLowerCase();
}

console.assert( type( null ) == 'null', 'null' );
console.assert( type( undefined ) == 'undefined', 'undefined' );
console.assert( type( [] ) == 'array', '[]' );
console.assert( type( {} ) == 'object', 'object' );
console.assert( type( false ) == 'boolean', 'false' );
console.assert( type( 1.2 ) == 'number', '1.2' );
console.assert( type( 'sogou' ) == 'string', 'sogou' );