var foo = [{ bar: 1, baz: [1,2,3] }, { bar: 2, baz: [4,5,6] }];
var filtered = $.grep(foo, function(v){
return v.bar === 1;
});
console.log(filtered);
Is there any way to modify a certain objects property (like the one I'm filtering out above) without creating new arrays and/or objects?
Desired result: [{ bar: 1, baz: [11,22,33] }, { bar: 2, baz: [4,5,6] }]
.map with spread (...) operator
var result = foo.map(el => el.bar == 1 ? {...el, baz: [11,22,33]} : el);
Sure, just change it:
With jQuery's $.each:
$.each(foo, function() {
if (this.bar === 1) {
this.baz[0] = 11;
this.baz[1] = 22;
this.baz[2] = 33;
// Or: `this.baz = [11, 22, 33];`
}
});
With ES5's forEach:
foo.forEach(function(obj) {
if (obj.bar === 1) {
obj.baz[0] = 11;
obj.baz[1] = 22;
obj.baz[2] = 33;
// Or: `obj.baz = [11, 22, 33];`
}
});
...or you have other looping options in this other SO answer.
You can use find and change its property.
let foo = [{ bar: 1, baz: [1,2,3] }, { bar: 2, baz: [4,5,6] }];
let obj = foo.find(f=>f.bar==1);
if(obj)
obj.baz=[2,3,4];
console.log(foo);
map like this answerWe can also achieve this by using Array's map function:
foo.map((obj) => {
if(obj.bar == 1){
obj.baz[0] = 11;
obj.baz[1] = 22;
obj.baz[2] = 33;
}
})
Without jQuery and backwards compatibility
for (var i = 0; i < foo.length; i++) {
if (foo[i].bar === 1) {
foo[i].baz = [11,12,13];
}
}
const objArr = [
{prop1: 'value1', prop2: 'value11'},
{prop1: 'value2', prop2: 'value22'},
{prop1: 'value3', prop2: 'option33'},
{prop1: 'value4', prop2: 'option44'}
]
const newObjArr = objArr.map(obj => {
if (['value1', 'value2'].includes(obj.prop1)) {
return {...obj, prop1: 'newValue'}
}
return obj
}
)
// const responseGotten = [
// { prop1: 'newValue', prop2: 'value11' },
// { prop1: 'newValue', prop2: 'value22' },
// { prop1: 'value3', prop2: 'option33' },
// { prop1: 'value4', prop2: 'option44' }
// ]
But before opting any of the mentioned techniques please keep in mind the performance challenges associated with each of the approach.
Object iterate For-In, average: ~240 microseconds.
Object iterate Keys For Each, average: ~294 microseconds.
Object iterate Entries For-Of, average: ~535 microseconds.
Reference - 3 JavaScript Performance Mistakes You Should Stop Doing
$.each(foo,function(index,value)
{
if(this.bar==1)
{
this.baz[0] = 11;
this.baz[1] = 22;
this.baz[2] = 33;
}
});
but for loop is faster than $.each so u can try to use
for(var i=0; i <foo.length; i++)
{
if(foo[i].bar==1)
{
//change the code
}
}
you can play around:
const tasks = [ { id: 1, done: false }, { id: 2, done: false } ]
const completed_task = { id: 1, done: true }
const markCompleted = (tasks, task) => {
const index = tasks.findIndex(t => t.id === task.id);
tasks.splice(index, 1);
tasks.push(task);
return tasks;
}
console.log(tasks)
console.log(markCompleted(tasks, completed_task))EDIT
to avoid index change:
const markCompleted = (tasks, task) => {
const index = tasks.findIndex(t => t.id === task.id);
tasks[index] = task;
return tasks;
}
You can make use of filter function of javascript.
obj = [
{inActive:false, id:1},
{inActive:false, id:2},
{inActive:false, id: 3}
];
let nObj = obj.filter(ele => {
ele.inActive = true;
return ele;
});
console.log(nObj);
You can modify the array by using simple for loop
var foo = [{ bar: 1, baz: [1,2,3] }, { bar: 2, baz: [4,5,6] }];
for(i = 0;i < foo.length;i++){
//Here your condition for which item you went to edit
if(foo[i].bar == 1){
//Here you logic for update property
foo[i].baz= [1,11,22]
}
}
console.log(foo);
let myArray = [
{ id: 1, body: "wash dishes", state: "done" },
{ id: 2, body: "wash car", state: "onGoing" },
{ id: 3, body: "wash hands", state: "done" },
]
myArray.findIndex(function(obj){ //it will search between every object in array
if (obj.body=="wash car"){ //find the object you looking for and pass to obj
obj.state = "done" // you can select and update any part you want here
}
console.log(myArray) // see the updatet array
