检查对象中是否存在值

Question

I have object:

var roles = { roles: [0: { name: 'admin' }, 1: { name: 'user' }] }

How I can check if value user exists?

I tried do:

console.log(('user' in roles));

But this return false . Why?

Answer 1

in operator checks for property not for it's values

 let test = {'a':1,'b':2} console.log('a' in test) console.log(1 in test) 

How can i search values

Here using some method of array i am checking whether desired value is in object or not.

 var roles = { roles: [{ name: 'admin' },{ name: 'user' }] } let searchValue = (input,searchKey) => { return input.some(( {name} ) => name === searchKey) // } console.log(searchValue(roles.roles, 'user')) console.log(searchValue(roles.roles, 'user not foound')) 

Answer 2

With a proper object, you could treat roles.roles as array and find the value with Array#some .

This works for any array like structure with an assignment to an array with Object.assign .

 function check(name) { return Object.assign([], roles.roles).some(o => o.name === name); } var roles = { roles: { 0: { name: 'admin' }, 1: { name: 'user' } } }; console.log(check('user')); console.log(check('bar')); 

By taking an array directly, you coult omit the assignment part.

 function check(name) { return roles.roles.some(o => o.name === name); } var roles = { roles: [{ name: 'admin' }, { name: 'user' }] }; console.log(check('user')); console.log(check('bar'));