How to set default value for NULL property in TypeScript

Question

I'm trying to set default value for all my NULL objects. Here's what I have

private setDisplayAmount(summaries: summary[]): void {
    summaries.map(t => {
        // do some magic, and then...
        this.setDefaultValueForEmptyAmounts(t);
    });
}

private setDefaultValueForEmptyAmounts(summary: Summary): void {
    Object.values(summary.displayAmounts).map(property => property || 0);
}

I've no idea why setDefaultValueForEmptyAmounts doesn't work properly...

This will work but is less esthetic:

private setDisplayAmount(summaries: summary[]): void {
    summaries.map(t => {
        // do some magic, and then...
        t.displayAmounts = {
            OneAmount: t.oneAmt || 0,
            TwoAmount: t.twoAmt || 0,
            // ... for all properties
        };

    });
}

Object.values(...).map(...) doesn't set values, only results in a array with the values — MarkB
– MarkB, Commented Sep 26, 2018 at 13:20
You probably want to change your maps to forEaches, and instead of doing Object.values().map(), you want Object.keys(x).forEach(k => x[k] = ...). Or just use for loops, if you don't understand how these functional programming methods work. — jcalz
– jcalz, Commented Sep 26, 2018 at 13:24

Anouar · Accepted Answer · 2018-09-26 13:23:52Z

2

When using map operations, you should always return something. But you could use forEach.

summaries.forEach(summary => {
    Object.keys(summary).forEach(key => {
    summary[key] = summary[key] || 0;
    });
});

answered Sep 26, 2018 at 13:23

Anouar

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