如何检查离子3中是否存在数组值

Question

I'm new to ionic 3. I'm geting an array which is selected from dropdown option: {"3":"5","4":"7"} .

now i need to check the dropdown value with this:

"variant_json": "{\"14\":\"5,7\",\"15\":\"5,8\",\"16\":\"6,7\",\"17\":\"6,8\"}"

For Example:

In dropdown, if i select 5,7 means it should check from "variant_json" and need to show its key is 14 .

Answer 1

You can use Object.keys and find

 let json = JSON.parse("{\\"14\\":\\"5,7\\",\\"15\\":\\"5,8\\",\\"16\\":\\"6,7\\",\\"17\\":\\"6,8\\"}") let findKeyByValue = (value) =>{ let found = Object.keys(json).find((key)=>json[key] === value) return found ? found : 'Not found' } console.log(findKeyByValue('5,7')) console.log(findKeyByValue('5,8')) console.log(findKeyByValue('9,9')) 

Answer 2

Use Object.entries :

 const obj = { "variant_json": "{\\"14\\":\\"5,7\\",\\"15\\":\\"5,8\\",\\"16\\":\\"6,7\\",\\"17\\":\\"6,8\\"}" }; const [, key ] = Object.entries(obj.variant_json).find(([k, v]) => v == "5,7"); console.log(key);