How to push string into array?

Question

Something magical happen. I'm stuck. How to push string into array?

const createParamForm = (paramsForms, setParamsForms) => {
  console.log('TCL: createParamForm -> paramsForms', paramsForms)
  const id = `f${(+new Date()).toString(16)}`
  console.log('TCL: createParamForm -> id', id)
  const paramsFormsClone = cloneDeep(paramsForms)
  console.log('TCL: createParamForm -> paramsFormsClone', paramsFormsClone)
  console.log(paramsFormsClone.push('banan'))
  // setParamsForms(newParamsForms)
}

The logs:

Why i'm getting 1 instead of ['banan'] ??

Because the _return value_ of `push` is the new length of the array, not the array itself. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/push — mbojko, Feb 05 '20 at 10:13

score 2 · Answer 1 · answered Feb 05 '20 at 10:13

2

Array push returns the new length of the array, not the actual values in it. Your'e fine.

answered Feb 05 '20 at 10:13

MorKadosh

5,846
3
25
37

score 1 · Answer 2 · answered Feb 05 '20 at 10:13

1

console.log(paramsFormsClone.push('banan')); statement return length of array.

Please check by using console.log(paramsFormsClone);

answered Feb 05 '20 at 10:13

Hiren Pipariya

80
8

Jins Thomas Shaji · Accepted Answer · 2020-02-05T10:19:09.850

Issue: Instead of logging paramsFormsClone, you have been logged operation paramsFormsClone.push('banan') which returns the new length of the array(1 here).

You have to change the code as:

const createParamForm = (paramsForms, setParamsForms) => {
  console.log('TCL: createParamForm -> paramsForms', paramsForms)
  const id = `f${(+new Date()).toString(16)}`
  console.log('TCL: createParamForm -> id', id)
  const paramsFormsClone = cloneDeep(paramsForms)
  console.log('TCL: createParamForm -> paramsFormsClone', paramsFormsClone)
  paramsFormsClone.push('banan')
  console.log(paramsFormsClone)
  // setParamsForms(newParamsForms)
}

score 1 · Answer 4 · answered Feb 05 '20 at 10:14

1

As push() returns the new length of the array after changes hence in your case it returns 1.

answered Feb 05 '20 at 10:14

xplatypus07

61
4

How to push string into array?

4 Answers4