the data goes like this:
var obj = [
{
id:1,
name:""
},
{
id:2,
name:""
},
{
id:3,
name:""
}
];
now I want to know what the subscript for "Xiao Hong" is for name
//,
function findIndex(arr,key,word){
arr.map((o,n)=>{
if(o[key] == word){
return n;
}
})
}
var t = findIndex(obj,"name","");
console.log(t); //underfineconst findIndex = (arr, key, word) => arr.findIndex(obj => obj[key] === word);function does not return a value, so it is undefined.
map is returned to the map array. In the question, arr.map is assigned [undedined,1,undefined] when he finishes running. So your findindex returns a null value. You can add a return before arr.map to see the return value.
can be changed to this, and that's fine.
function findIndex(arr,key,word){
arr.map((o,n)=>{
if(o[key] == word){
console.log(n);
}
});
} 
function findIndex(arr,key,word){
return arr.find(item => {
return item.name === word
})
}
var t = findIndex(obj,'name','');
console.log(t); //{id: 2, name: ""} your findIndex has no return value, brother dei
you define a variable outside the map function, and
assign a value in the map.
Last return outside the map function
how to break down components, there will be a lot of communication code between components, and the loss outweighs the gain, but in this way, there is too much code, which is difficult to maintain. is there any good solution, The page has five piece...
the following article probably talks about https: blog.csdn.net kittyji. there are two types of my methods one needs to verify whether the user is logged in. If you have logged in, you can directly call the background interface, and if you do not...
the following is a copy of the official document, but I haven t figured out the difference between the two methods sometimes you may need to assign multiple new properties to existing objects, such as using Object.assign () or _ .extend (). In this c...